ARM: OMAP: Kill warning in CPUIDLE code with !CONFIG_SMP

for non SMP build, NR_CPUS is 1 and hence the code complains with below
warnings.

arch/arm/mach-omap2/cpuidle44xx.c:207:8: warning: array subscript is above array bounds [-Warray-bounds]
arch/arm/mach-omap2/cpuidle44xx.c:212:11: warning: array subscript is above array bounds [-Warray-bounds]

Kill it by making array size fixed.

Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>