[ARM] 5032/1: Added cpufreq support for pxa27x CPU

PXA cpus maximum frequency depends on the cpu (624 for
pxa270, 520 for pxa272, 416 for pxa271). It should be
provided on kernel or module start (cpu-pxa
pxa27x_maxfreq parameter).

Make use of cpufreq_frequency_table_cpuinfo (patch by Bill
Reese provided by Philipp Zabel).

Some additionnal fixes from Philipp Zabel include :
 * rename PXA cpufreq driver to reflect added PXA27x support
 * remove unused variable ramstart from PXA cpufreq driver

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <rjarzmik@free.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>