Rename the source file for DMA for SDHI as a follow-up to attaching
DMA code to the SDHI driver rather than the tmio_core driver.

The name "renesas" is chosen as the SDHI driver is applicable to a wider
range of SoCs than SH-Mobile it seems to be a more appropriate name.
However, the SDHI driver source itself, is left as sh_mobile_sdhi to
avoid unnecessary churn.

The name sys_dmac was chosen to reflect the type of DMA used.

Internal symbols have also been renamed to reflect the filename change.

A follow-up patch will re-organise the SDHI driver removing
the need for renesas_sdhi_get_dma_ops().
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>