pinctrl: sh-pfc: r8a7779: Fix missing MOD_SEL2 entry

The list of functions selected by the MOD_SEL2 register was missing
an entry. This caused all entries after this to modify the MOD_SEL2
register incorrectly.

This bug showed up when selecting i2c2_c pins on the Renesas Hurricane board.

This bug has been present since pinmux support was added for the
r8a7779 SoC by 881023d2 ("sh-pfc: Add
r8a7779 pinmux support") in v3.8-rc4.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>