usb: phy-msm-qusb-v2: Shift the read minor revision value

This is required to read the proper minor revision value
from the nvmem.
(Documentation/devicetree/bindings/nvmem/nvmem.txt)
Nvmem has the offset limit bits set to 0 and to read the
bits 28-29 the consumers have to right shift it by 28.

Change-Id: I46962a3cffbf45e904a23417d668052582b487c0
Signed-off-by: Pratham Pratap <prathampratap@codeaurora.org>