🐛 Fix Lerdge USB Flash Drive envs (#21847)

ini/stm32f4.ini

 platform          = ${env:LERDGEX.platform}
 extends           = env:LERDGEX
 platform_packages = ${stm_flash_drive.platform_packages}
-build_flags       = ${stm_flash_drive.build_flags}
+build_flags       = ${stm_flash_drive.build_flags} ${lerdge_common.build_flags}
 
 #
 # Lerdge S
 platform          = ${env:LERDGES.platform}
 extends           = env:LERDGES
 platform_packages = ${stm_flash_drive.platform_packages}
-build_flags       = ${stm_flash_drive.build_flags}
+build_flags       = ${stm_flash_drive.build_flags} ${lerdge_common.build_flags}
 
 #
 # Lerdge K
 platform          = ${env:LERDGEK.platform}
 extends           = env:LERDGEK
 platform_packages = ${stm_flash_drive.platform_packages}
-build_flags       = ${stm_flash_drive.build_flags}
+build_flags       = ${stm_flash_drive.build_flags} ${lerdge_common.build_flags}
 
 #
 # RUMBA32