MIPS: Move 'gic_frequency' to common location.

Move the global variable 'gic_frequency' to be defined in the file
'arch/mips/kernel/irq-gic.c' instead of defining it individually
for each platform making use of the GIC. Also change the type to
be an unsigned integer instead of signed.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>

arch/mips/kernel/irq-gic.c

@@ -19,6 +19,7 @@
 #include <linux/hardirq.h>
 #include <asm-generic/bitops/find.h>
 
+unsigned int gic_frequency;
 unsigned int gic_present;
 unsigned long _gic_base;
 unsigned int gic_irq_base;