ARM: dts: aspeed: bletchley: Update and fix gpio-line-names

Update new GPIOM7 line name, and fixed typo of GPION6 line name

New GPIO:
- GPIOM7: USB_DEBUG_PWR_BTN_N

Fixed GPIO:
- GPION6: LED_POSTCODE_5 --> LED_POSTCODE_6

Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
Reviewed-by: Patrick Williams <patrick@stwcx.xyz>
Link: https://lore.kernel.org/r/20220929013130.1916525-2-potin.lai.pt@gmail.com


Signed-off-by: Joel Stanley <joel@jms.id.au>