ARM: shmobile: defconfig: add MTD_BLOCK

MTD_BLOOK is needed for accessing to SPI-FLASH

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reported-by: Cao Minh Hiep <cm-hiep@jinso.co.jp>
Reported-by: Bui Duc Phuc ( Fukuda ) <bd-phuc@jinso.co.jp>
Reported-by: Nguyen Xuan Nui <nx-nui@jinso.co.jp>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>