sdm: Add new line character to mode string

Driver expects new line character in mode string
for dynamic resolution switch feature.
std::getline (unlike ::getline) removes \n
while driver expects it in mode, so add back

Change-Id: I2687c2ba8fa8ea0a1ac61fb24e92c7ee7387af8d
CRs-Fixed: 1044010
1 file changed