serial: pl011: remove samsung's own workaround for corruption at high clock speeds

this causes more data corruption as it conflicts with st-ericsson's workaround at e1eff59615a6395758318d7c6f760eccf7ddef62. turns out the stupid bt issues was due to samsung's own workaround conflicting with st-ericsson's in linux 3.0.45 :|

Change-Id: I0eb3c33201fd968509ecfa78b86535c0062010d3