ARM: sirf: use CONFIG_SIRF rather than CONFIG_PRIMA2 where necessary

I got a build error today that made me realize that it is not
possible to build a kernel for a SiRF platform without enabling
CONFIG_PRIMA2, since a lot of common code depends on CONFIG_PRIMA2.

This fixes all occurences that appear like common SiRF code.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Mark Brown <broonie@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Barry Song <Baohua.Song@csr.com>
Acked-by: Mike Turquette <mturquette@linaro.org>