[IA64] move SAL_CACHE_FLUSH check later in boot

The check to see if the firmware drops interrupts during a
SAL_CACHE_FLUSH is done to early in the boot. SAL_CACHE_FLUSH expects
to be able to make PAL calls in virtual mode, on some cell based
machines a fault occurs causing a MCA. This patch moves the check
after mmu_context_init so the TLB and VHPT are properly setup.

Signed-off-by Troy Heber <troy.heber@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/asm-ia64/sal.h b/include/asm-ia64/sal.h
index 0b210ab..d000689 100644
--- a/include/asm-ia64/sal.h
+++ b/include/asm-ia64/sal.h
@@ -659,6 +659,7 @@
 }
 
 extern s64 ia64_sal_cache_flush (u64 cache_type);
+extern void __init check_sal_cache_flush (void);
 
 /* Initialize all the processor and platform level instruction and data caches */
 static inline s64