mmc: msm_sdcc: Add new soft reset mechanism for SDCCv4

Newer versions of SDCCv4 controller has added a soft
reset mechanism to reset the controller state machine
or reset the entire controller to default power on state.

MCI_POWER[SW_RST] - The impact of this reset bit will be
similar to the impact of the reset by doing clk_reset() on
host controller clock (HCLK). With this all SW registers
and all internal logic is reset.

MCI_POWER[SW_RST_CONFIG] - Resets the controller state machines
without resetting configuration registers (MCI_POWER, MCI_CLK,
MCI_INT_MASKn).

Change-Id: I7fd13e736b23dff16c20bd9f865ca97e7daaf304
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>