MAINTAINERS: fix arch/arm/plat-omap/include/plat/omap_hwmod.h

This file was moved to arch/arm/mach-omap2/omap=5Fhwmod.h by commit
2a296c8f ("ARM: OMAP: Make plat/omap=5Fhwmod.h local to
mach-omap2").

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>