spelling fixes: arch/um/

Spelling fixes in arch/um/.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>

arch/um/sys-x86_64/bug.c

@@ -6,7 +6,7 @@
 #include <linux/uaccess.h>
 
 /* Mostly copied from i386/x86_86 - eliminated the eip < PAGE_OFFSET because
- * that's not relevent in skas mode.
+ * that's not relevant in skas mode.
  */
 
 int is_valid_bugaddr(unsigned long eip)