irqchip/mips-gic: Mark count and compare accessors notrace

gic_read_count(), gic_write_compare() and gic_write_cpu_compare() are
often used in a sequence to update the compare register with a count
value increased by a small offset.
With small delta values used to update the compare register, the time to
update function trace for these operations may be longer than the update
timeout leading to update failure.

Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-mips@linux-mips.org
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1496991845-27031-1-git-send-email-marcin.nowakowski@imgtec.com