usb: dwc3-msm: Program MSB of doorbell register when using dummy_addr

Driver currently assumes that dma mapped address for doorbell register
would be 32 bit only. This assumption works fine for real doorbell
register. However, if memory address is used as dummy doorbell register
then we must program MSB register as well as buffer address could be
more than 32 bits if IOMMU is not enabled with USB. If IOMMU is enabled
then dma-mapped address would always be of 32 bits and this issue won't
be seen.

Change-Id: Id33117830dfebe60216bdf035d2530d584dc6b6b
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>