usb: musb: dma: Remove unused variable

Remove unused-but-set devctl variable.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20210123142502.16980-3-paul@crapouillou.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>