xtensa: fix Kconfig typo

Correct trivial typo (ful -> full).

Fixes: 76743c0e0915 ("xtensa: move kernel memory layout to platform options")
Signed-off-by: Randy Dunlap <[email protected]>
Cc: Chris Zankel <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: [email protected]
Acked-by: Max Filippov <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

arch/xtensa/Kconfig

@@ -537,7 +537,7 @@ config MEMMAP_CACHEATTR
 	    2: cache bypass,
 	    4: WB cached,
 	    f: illegal.
-	  For ful MMU:
+	  For full MMU:
 	    bit 0: executable,
 	    bit 1: writable,
 	    bits 2..3: