msm: Adding config for r8125 driver

Add config to enable Realtek's r8125 driver.

Change-Id: I00cc2344d4705cd84156a44e30c4645d54df2008
Acked-by: Lakshit Tyagi <ltyagi@codeaurora.org>
Signed-off-by: Karthik Rudrapatna <krudrapa@codeaurora.org>