usb: gadget: clean-up msm_usb_bam_platform_data structure

Due to changes in usb_bam driver and usage of the
standard mechanism of platform resources instead
of adding new platform data, usb_bam_phy_base and
usb_bam_phy_size fields became unnecessary and were
removed.

Change-Id: I0f3a57724ecc033e704aaca6f651561a344c9fef
Signed-off-by: Ofir Cohen <ofirc@codeaurora.org>