nrf/mphalport: Remove need for "syntax unified" in mp_hal_delay_us.
Because it can confuse older versions of gcc.  Instead use the correct
instruction for Thumb vs (sub vs subs) so the assembler emits the
2-byte instruction.
Related to commit
@@ -99,11 +99,12 @@ void mp_hal_delay_us(mp_uint_t us) {
}
register uint32_t delay __ASM("r0") = us;
__ASM volatile (
- #ifdef NRF51
- ".syntax unified\n"
- #endif
"1:\n"
+ #ifdef NRF51
+ " SUB %0, %0, #1\n"
+ #else
" SUBS %0, %0, #1\n"
+ #endif
" NOP\n"
" NOP\n"
" NOP\n"
