phy: msm: ssusb: Enable SSC modulation for fixing SS compliance failures

It is required to enable SSC modulation overrides in SSC_OVRD_IN register
for passing electrical compliance tests like SSC Modulation Rate and
TSSC-Freq-Dev-Min tests and also for fixing lecroy physical layer test
"ch6.3: Elastic buffer test".

Change-Id: Ifd3d865e03db766775f9a91e1baedc8b51de94ca
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>