usb: ehci-msm2: Set dma bit mask to 32

ChipIdea USB controller supports only 32 bit addressing. Some targets
support 64 bit or 32 bit addressing. In order to support ChipIdea
controller on 64 bit targets dma bit mask must be defined as 32.

Change-Id: I2fa0c9bb2efa9879520a3ca04c8950e34609a3f1
Signed-off-by: Azhar Shaikh <azhars@codeaurora.org>