[ARM] 5533/1: Add U300 series defconfig

This adds a defconfig for the U300 series ST-Ericsson mobile
platforms. It will be maintained to enable the maximum set of
drivers so as to provide a good regression testing target for
these platforms.
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>