During boot, we detect whether or not all CPUs are brought up in the
same mode and signal this to the kernel using the N bit in the SPSR.
This patch tidies up the checking code to use the PSR_N_BIT macro,
rather than hardcoding the bit field and commenting it as such.
Signed-off-by: Will Deacon <will.deacon@arm.com>
4e3c194480