metag: cachepart: fix get_global_dcache_size() typo

Compilation is broken when the kernel is destined to live in the global
part of the virtual address space:

arch/metag/kernel/cachepart.c In function 'get_thread_cache_size':
arch/metag/kernel/cachepart.c +71 : error: implicit declaration of function 'get_global_dache_size'

Fix the typo.
Signed-off-by: James Hogan <james.hogan@imgtec.com>

arch/metag/kernel/cachepart.c

@@ -67,7 +67,7 @@ static unsigned int get_thread_cache_size(unsigned int cache, int thread_id)
 		return 0;
 #if PAGE_OFFSET >= LINGLOBAL_BASE
 	/* Checking for global cache */
-	cache_size = (cache == DCACHE ? get_global_dache_size() :
+	cache_size = (cache == DCACHE ? get_global_dcache_size() :
 		get_global_icache_size());
 	offset = 8;
 #else