mmc: octeontx_hsmmc: Add support for MIPS Octeon

Until now, the Octeontx MMC driver did only support the ARM Octeon
TX/Tx2 platforms. This patch adds support for the MIPS Octeon platform
to this driver. Here a short summary of the changes:

- Enable driver compilation for MIPS Octeon, including the MMC related
header file
- Reorder header inclusion
- Switch to using the clk framework to get the input clock
- Remove some functions for MIPS Octeon, as some registers don't
exist here

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Aaron Williams <awilliams@marvell.com>
Cc: Chandrakala Chavva <cchavva@marvell.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>