musb: am35x: fix compile error due to control apis

commit 4814ced5 (OMAP:
control: move plat-omap/control.h to mach-omap2/control.h)
moved <plat/control.h> to another location, preventing
drivers from accessing it, so we need to pass function
pointers from arch code to be able to talk to internal
PHY on AM35x.

Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>