serial/amba-pl011: fix ages old copy-paste errors

The PL011 driver has a number of symbols referring to "pl01x"
(probably once shared with the pl010 driver) and some even named
"pl010" (probably a pure copy-paste artifact). Lets name all
local static functions with the prefix pl011_* for clarity.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>