um: Remove outdated comment about STUB_DATA_PAGES

STUB_DATA_PAGES is no longer required to be a power of two since
commit 91f0a0c ("um: Calculate stub data address relative to
stub code"). Remove the outdated comment.

Signed-off-by: Tiwei Bie <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>

Author: btw616

arch/um/include/shared/as-layout.h

@@ -23,7 +23,7 @@
 #define STUB_START stub_start
 #define STUB_CODE STUB_START
 #define STUB_DATA (STUB_CODE + UM_KERN_PAGE_SIZE)
-#define STUB_DATA_PAGES 2 /* must be a power of two */
+#define STUB_DATA_PAGES 2
 #define STUB_END (STUB_DATA + STUB_DATA_PAGES * UM_KERN_PAGE_SIZE)
 
 #ifndef __ASSEMBLER__