usb: musb: blackfin: include prefetch head file
usb: musb: blackfin: include prefetch head file

After the prefetch/list.h restructure, drivers need to explicitly include
linux/prefetch.h in order to use the prefetch() function.  Otherwise, the
current driver fails to build:
drivers/usb/musb/blackfin.c: In function 'musb_write_fifo':
drivers/usb/musb/blackfin.c:43: error: implicit declaration of function
'prefetch'

Signed-off-by: Bob Liu <d77a20a83082b67b4fa80a32c4df5692104d5480@gmail.com>
Signed-off-by: Felipe Balbi <94dddeeef08b001e003cce128ddc162a4e2c6cd2@ti.com>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas