Kconfig: Migrate BOUNCE_BUFFER

The bounce buffer is used by a few drivers (most of the MMC drivers)
to overcome limitations in their respective DMA implementation.

This moves the configuration to Kconfig and makes it user-selectable
(even though it will be a required feature to make those drivers
work): the expected usage is for drivers depending on this to 'select'
it unconditionally from their respective Kconfig (see follow-up
patches).

This commit includes a full migration using moveconfig.py to ensure
that each commit compiles.  To ensure bisectability we update
dependencies of various drivers to now select BOUNCE_BUFFER when needed.

[trini: Squash all patches to ensure bisectability]
Signed-off-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Otavio Salvador <otavio@ossystems.com.br> [dw_mmc portion]
Reviewed-by: Fabio Estevam <festevam@gmail.com> [mxsmmc portion]
Reviewed-by: Simon Glass <sjg@chromium.org> [tegra portion]
diff --git a/configs/cm_fx6_defconfig b/configs/cm_fx6_defconfig
index d6726f6..c8d1e83 100644
--- a/configs/cm_fx6_defconfig
+++ b/configs/cm_fx6_defconfig
@@ -19,6 +19,7 @@
 CONFIG_BOOTDELAY=3
 CONFIG_BOOTCOMMAND="run findfdt; run distro_bootcmd; run legacy_bootcmd"
 CONFIG_MISC_INIT_R=y
+CONFIG_BOUNCE_BUFFER=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0x80
 CONFIG_SPL_I2C_SUPPORT=y
 CONFIG_SPL_SPI_LOAD=y