btrfs: use generic Kconfig option for 256kB page size limit

Use the newly introduced CONFIG_PAGE_SIZE_LESS_THAN_256KB to describe
the dependency introduced by commit b05fbcc ("btrfs: disable build
on platforms having page size 256K").

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Nathan Chancellor <[email protected]>
Acked-by: David Sterba <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: nathanchance

fs/btrfs/Kconfig

@@ -18,8 +18,7 @@ config BTRFS_FS
 	select RAID6_PQ
 	select XOR_BLOCKS
 	select SRCU
-	depends on !PPC_256K_PAGES	# powerpc
-	depends on !PAGE_SIZE_256KB	# hexagon
+	depends on PAGE_SIZE_LESS_THAN_256KB
 
 	help
 	  Btrfs is a general purpose copy-on-write filesystem with extents,