usb: musb: Enable DMA mode1 RX for transfers without short packets

This patch enables DMA mode1 for the RX path when we know
there won't be any short packets. We check that by looking
into the short_no_ok flag, if it's true we enable mode1, otherwise
we use mode0 to transfer the data.

This will result in a throughput performance gain of around
40% for USB mass-storage/mtp use cases.

[ balbi@ti.com : updated commit log and code comments slightly ]

Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
Signed-off-by: Vikram Pandita <vikram.pandita@ti.com>
Tested-by: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>