serial/amba-pl011: use devm_* managed resources

This switches a bunch of allocation and remapping to use the
devm_* garbage collected methods and cleans up the error
path and remove() paths consequently.

devm_ioremap() is only in <linux/io.h> so fix up the
erroneous <asm/*> include as well.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Domenico Andreoli <domenico.andreoli@linux.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>