usb: musb: ux500_dma: fix sparse warning
usb: musb: ux500_dma: fix sparse warning

fix the following sparse warning:

drivers/usb/musb/ux500_dma.c:60:6: warning: symbol 'ux500_dma_callback' was not declared. Should it be static?

Signed-off-by: Felipe Balbi <94dddeeef08b001e003cce128ddc162a4e2c6cd2@ti.com>

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