pinctrl: renesas: Move R-Car bias helpers to sh_pfc.h

The Renesas Pin Function Controller driver uses two header files:
- sh_pfc.h, for use by both core code and SoC-specific drivers,
- core.h, for internal use by the core code only.

Hence move the R-Car bias helper declarations from core.h to sh_pfc.h,
and drop the inclusion of core.h from SoC-specific drivers that no
longer need it.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20210303132619.3938128-3-geert+renesas@glider.be

pinctrl: renesas: Make sh_pfc_pin_to_bias_reg() static

Now all R-Car pin control drivers have been converted to the common
R-Car bias handling, sh_pfc_pin_to_bias_reg() is only called from a
single place. Move it from core.c to pinctrl.c, make it static, and
rename it to rcar_pin_to_bias_reg(), as it is specific to R-Car SoCs.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20210303132619.3938128-2-geert+renesas@glider.be

pinctrl: renesas: Factor out common R-Car Gen3 bias handling

All pin control drivers for R-Car Gen3 SoCs contain identical bias
handling. Reduce code duplication by moving it to the common pinctrl.c
code.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20201028151637.1734130-6-geert+renesas@glider.be

pinctrl: Rename sh-pfc to renesas

The drivers/pinctrl/sh-pfc subdirectory was originally created to group
pin control drivers for various Renesas SuperH and SH-Mobile platforms.
However, the name "sh-pfc" no longer reflects its contents, as the
directory now contains pin control drivers for Renesas SuperH, ARM32,
and ARM64 SoCs.

Hence rename the subdirectory from drivers/pinctrl/sh-pfc to
drivers/pinctrl/renesas, and the related Kconfig symbol from
PINCTRL_SH_PFC to PINCTRL_RENESAS.

Rename the git branch in MAINTAINERS, too, for consistency.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200909131534.12897-3-geert+renesas@glider.be