mmc/dw_mmc: Add support for ARC

* Adapt Kconfig to include ARC in supported architectures
* Make host->bus_hz default to the given bus rate (in devicetree), for
  platforms where clk_get_rate is unsupported and always returns 0.

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
ARC: Add basic support for HAPS51

Support for UART, Ethernet and MMC

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
ARC: [haps51] Add defconfig

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
input/serio: disable i8042 PC keyboard ctrl for ARC

It causes crashes when enabled, and we don't have such a peripheral
anyway on ARC platforms.

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
serial/arc-uart: Clear interrupts when encountering errors

If we get a frame error or overflow error without actually receiving
characters, the interrupt will not be cleared. This patch fixes this
problem by checking for these bits in the interrupt handler.

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
Cc: Vineet Gupta <vgupta@synopsys.com>