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/20211129230141.228085-3-nathan@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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,