musb: use dma mode 1 for TX if transfer size equals maxpacket (v2)

Currently, with Inventra DMA, we use Mode 0 if transfer size is less
than or equal to the endpoint's maxpacket size.  This requires that
we explicitly set TXPKTRDY for that transfer.

However the musb_g_tx code will not set TXPKTRDY twice if the last
transfer is exactly equal to maxpacket, even if request->zero is set.
Using Mode 1 will solve this; a better fix might be in musb_g_tx().

Without this change, musb will not correctly send out a ZLP if the
last transfer is the maxpacket size and request->zero is set.

Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>