ARM: msm: export legacy DMA interfaces

The msm_sdcc MMC driver and the msm_serial_hs uart driver both
use the pre-dmaengine interfaces provided by the MSM platform.

Since these drivers can be loadable modules, we should export
the functions used in the drivers.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Brown <davidb@codeaurora.org>
Cc: Daniel Walker <dwalker@fifo99.com>
Cc: Bryan Huntsman <bryanh@codeaurora.org>