ASoC: pxa: i2s: use normal MMIO accessors

To avoid dereferencing hardwired constant pointers from a global header
file, change the driver to use devm_platform_ioremap_resource for getting
an __iomem pointer, and then using readl/writel on that.

Each pointer dereference gets changed by a search&replace, which leads
to a few overlong lines, but seems less risky than trying to clean up
the code at the same time.

Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: alsa-devel@alsa-project.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>