xtensa: remove redefinition of XCHAL_MMU_ASID_BITS

This constant is defined in all core headers.  Remove the redundant
definition which might error out if other includes lead to inclusion
of <variant/core.h>.
Signed-off-by: Johannes Weiner <jw@emlix.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

arch/xtensa/include/asm/mmu_context.h

@@ -16,13 +16,13 @@
 #include <linux/stringify.h>
 #include <linux/sched.h>
 
+#include <variant/core.h>
+
 #include <asm/pgtable.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm-generic/mm_hooks.h>
 
-#define XCHAL_MMU_ASID_BITS	8
-
 #if (XCHAL_HAVE_TLBS != 1)
 # error "Linux must have an MMU!"
 #endif