ARM: OMAP2+: hwmod: Remove unused _HWMOD_WAKEUP_ENABLED flag

_HWMOD_WAKEUP_ENABLED is currently unused across the hwmod
framework. Just get rid of it, so we have one less flag to
worry about.

Tested-by: Vaibhav Bedia <vaibhav.bedia@ti.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>