usb: musb: omap: fix crash when musb glue (omap) gets initialized

pm_runtime_enable is being called after omap2430_musb_init. Hence
pm_runtime_get_sync in omap2430_musb_init does not have any effect (does
not enable clocks) resulting in a crash during register access. It is
fixed here.

Cc: stable@vger.kernel.org # v3.0, v3.1, v3.2, v3.3
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>