ARM/ASoC: omap-mcbsp: Remove CLKR/FSR mux configuration code

Remove the feature to configure the CLKR/FSR mux on McBSP port with 6pin
configuration.
When moving to devicetree these callback can no longer be used in a clean
way anymore.
If a board require to change the 6pin port to work in 4pin setup it needs
to set up the mux in the board file.
For OMAP2/3:
u32 devconf0;

/* McBSP1 CLKR/FSR signal to be connected to CLKX/FSX pin */
devconf0 = omap_ctrl_readl(OMAP2_CONTROL_DEVCONF0);
devconf0 |=  OMAP2_MCBSP1_CLKR_MASK | OMAP2_MCBSP1_FSR_MASK;
omap_ctrl_writel(devconf0, OMAP2_CONTROL_DEVCONF0);

For OMAP4:
u32 mcbsp_pad;

/* McBSP4 CLKR/FSR signal to be connected to CLKX/FSX pin */
mcbsp_pad = omap4_ctrl_pad_readl(OMAP2_CONTROL_DEVCONF0);
mcbsp_pad |=  ((1 << 31) | (1 << 30));
omap4_ctrl_pad_writel(mcbsp_pad, OMAP2_CONTROL_DEVCONF0);

In case when the kernel is booted with DT blob the pinctrl-single will be
provided as soon as it is enabled on the platform.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>