ARM: shmobile: bockw: enable CONFIG_DEVTMPFS in defconfig

This reverts commit e14ee5de
("ARM: shmobile: bockw: Do not enable CONFIG_DEVTMPFS defconfig").

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
[horms+renesas@verge.net.au: Added subject of reverted commit to changelog]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>