pinctrl: sh-pfc: r8a7791: Add missing HSCIF1 pinmux data

The R8A7791 PFC driver  was apparently based on the preliminary revisions
of  the  user's manual, which  omitted the HSCIF1 group E signals in  the
IPSR4 register description. This would cause HSCIF1's probe  to fail with
the messages like below:

sh-pfc e6060000.pfc: cannot locate data/mark enum_id for mark 1989
sh-sci e62c8000.serial: Error applying setting, reverse things back
sh-sci: probe of e62c8000.serial failed with error -22

Add the neceassary PINMUX_IPSR_MSEL() invocations for the HSCK1_E,
HCTS1#_E, and HRTS1#_E signals...

Fixes: 50884519 ("pinctrl: sh-pfc: r8a7791 PFC support")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>