pinctrl: sh-pfc: sh7734: Fix duplicate TCLK1_B

The definitions for bit field [19:18] of the Peripheral Function Select
Register 3 were accidentally copied from bit field [20], leading to
duplicates for the TCLK1_B function, and missing TCLK0, CAN_CLK_B, and
ET0_ETXD4 functions.

Fix this by adding the missing GPIO_FN_CAN_CLK_B and GPIO_FN_ET0_ETXD4
enum values, and correcting the functions.

Reported-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20191024131308.16659-1-geert+renesas@glider.be