Fixed warning about comparing signed to unsigned (#11909)

Marlin/src/HAL/HAL_DUE/EepromEmulation_Due.cpp

           //  Maybe we could coalesce the next block with this block. Let's try to do it!
           uint16_t inext = i + 3 + blen;
           if (inext <= (PageSize - 4) &&
-            (buffer[inext] | (uint16_t(buffer[inext + 1]) << 8)) == (baddr + blen + 1)) {
+            (buffer[inext] | uint16_t(buffer[inext + 1] << 8)) == (baddr + blen + 1)) {
             // YES! ... we can coalesce blocks! . Do it!
 
             // Adjust this block header to include the next one