ARM: l2c: remove outer_inv_all() method

No one ever calls this function anywhere in the kernel, so let's
completely remove it from the outer cache API and turn it into an
internal-only thing.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/cache-feroceon-l2.c

@@ -350,7 +350,6 @@ void __init feroceon_l2_init(int __l2_wt_override)
 	outer_cache.inv_range = feroceon_l2_inv_range;
 	outer_cache.clean_range = feroceon_l2_clean_range;
 	outer_cache.flush_range = feroceon_l2_flush_range;
-	outer_cache.inv_all = l2_inv_all;
 
 	enable_l2();