mtd: Make CONFIG_MTD be the gate symbol for the menu

The help for CONFIG_MTD explains that it needs to be enabled for various
things like NAND, etc to be available. It however then doesn't enforce
this dependency and so if you have none of these systems present you
still need to disable a number of options. Fix this by making places
that select/imply one type of flash, but did not do the same, also do
this for "MTD". Make boards which hadn't been enabling MTD already but
need it now, do so. In a few places, disable CONFIG_CMD_MTDPARTS as it
wasn't previously enabled but was now being implied.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/pinecube_defconfig b/configs/pinecube_defconfig
index 1551cf1..7cc0a86 100644
--- a/configs/pinecube_defconfig
+++ b/configs/pinecube_defconfig
@@ -14,6 +14,7 @@
 CONFIG_SYS_I2C_MVTWSI=y
 CONFIG_SYS_I2C_SLAVE=0x7f
 CONFIG_SYS_I2C_SPEED=400000
+CONFIG_MTD=y
 CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_AXP209_POWER=y
 CONFIG_AXP_DCDC2_VOLT=1250