🎨 Misc. USB flash code cleanup

Marlin/src/sd/usb_flashdrive/Sd2Card_FlashDrive.cpp

   #define USB_NO_TEST_UNIT_READY // Required for removable media adapter
   #define USB_HOST_MANUAL_POLL // Optimization to shut off IRQ automatically
 
-  // Workarounds for keeping Marlin's watchdog timer from barking...
-  void marlin_yield() {
-    thermalManager.manage_heater();
-  }
+  // Workarounds to keep Marlin's watchdog timer from barking...
+  void marlin_yield() { thermalManager.manage_heater(); }
   #define SYSTEM_OR_SPECIAL_YIELD(...) marlin_yield();
   #define delay(x) safe_delay(x)
 
 
   #define UHS_START  (usb.Init() == 0)
   #define UHS_STATE(state) UHS_USB_HOST_STATE_##state
+
 #elif ENABLED(USE_OTG_USB_HOST)
 
   #if HAS_SD_HOST_DRIVE
   #define UHS_START usb.start()
   #define rREVISION 0
   #define UHS_STATE(state) USB_STATE_##state
+
 #else
+
   #include "lib-uhs2/Usb.h"
   #include "lib-uhs2/masstorage.h"
 
 
   #define UHS_START usb.start()
   #define UHS_STATE(state) USB_STATE_##state
+
 #endif
 
 #include "Sd2Card_FlashDrive.h"
   if (!isInserted()) return false;
 
   #if USB_DEBUG >= 1
-  const uint32_t sectorSize = bulk.GetSectorSize(0);
-  if (sectorSize != 512) {
-    SERIAL_ECHOLNPGM("Expecting sector size of 512. Got: ", sectorSize);
-    return false;
-  }
+    const uint32_t sectorSize = bulk.GetSectorSize(0);
+    if (sectorSize != 512) {
+      SERIAL_ECHOLNPGM("Expecting sector size of 512. Got: ", sectorSize);
+      return false;
+    }
   #endif
 
   #if USB_DEBUG >= 3

Marlin/src/sd/usb_flashdrive/lib-uhs2/usbhost.cpp

 
 #if ENABLED(USB_FLASH_DRIVE_SUPPORT) && DISABLED(USE_UHS3_USB)
 
+#if !PINS_EXIST(USB_CS, USB_INTR)
+  #error "USB_FLASH_DRIVE_SUPPORT requires USB_CS_PIN and USB_INTR_PIN to be defined."
+#endif
+
 #include "Usb.h"
 #include "usbhost.h"
 
 uint8_t MAX3421e::vbusState = 0;
 
 // constructor
-void MAX3421e::cs() {
-  WRITE(USB_CS_PIN,0);
-}
-
-void MAX3421e::ncs() {
-  WRITE(USB_CS_PIN,1);
-}
+void MAX3421e::cs()  { WRITE(USB_CS_PIN, LOW); }
+void MAX3421e::ncs() { WRITE(USB_CS_PIN, HIGH); }
 
 // write single byte into MAX3421 register
 void MAX3421e::regWr(uint8_t reg, uint8_t data) {
   ncs();
   return rv;
 }
-// multiple-byte register read
 
+// multiple-byte register read
 // return a pointer to a memory position after last read
 uint8_t* MAX3421e::bytesRd(uint8_t reg, uint8_t nbytes, uint8_t *data_p) {
   cs();
   ncs();
   return data_p;
 }
-// GPIO read. See gpioWr for explanation
 
+// GPIO read. See gpioWr for explanation
 // GPIN pins are in high nybbles of IOPINS1, IOPINS2
 uint8_t MAX3421e::gpioRd() {
   return (regRd(rIOPINS2) & 0xF0) | // pins 4-7, clean lower nybble