Fix ARMC6 guard typo introduced in commit 4f3f0cc9cc (Make Realtek link)
While at it, remove redundant ISR_STACK_SIZE assignment for ARMCC.
Signed-off-by: Tony Wu <tonywu@realtek.com>
There was some interesting stuff here.
* ARMC6 treats assembly the same as GNU, but has a different startup
function, so we branch the asm there
* Incorrect discriminant, probably copied from other ports