memshare: Add snapshot of memshare driver

The patch is a snapshot of memshare driver taken from msm-4.9 commit
<fce0dd25c02> (Merge "usb: phy: snps: Use external resistor (REXT)
for HSTX tuning").

Change-Id: I529f40a089d5c7f1baa2aeb5112f8e1aeb3a48a9
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>