ARM: OMAP2+: omap_hwmod: provide space for more hwmod flags

'flags' member of omap_hwmod structure is fast running
out of space with 16 different flags already defined.

Make flags a 32-bit entity so as to allow for more flags.

This results is a ~2.3K data section size increase with
omap2plus_defconfig on v4.11-rc2.

before:
   text	   data	    bss	    dec	    hex	filename
8186930	3082444	8252992	19522366	129e33e	vmlinux

after:
   text	   data	    bss	    dec	    hex	filename
8186922	3084812	8252992	19524726	129ec76	vmlinux

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>