pinctrl: sh-pfc: r8a77990: Fix MOD_SEL0 SEL_I2C1 field width

The SEL_I2C1 (MOD_SEL0[21:20]) field in Module Select Register 0 has a
width of 2 bits, i.e. it allows programming one out of 4 different
configurations.
However, the MOD_SEL0_21_20 macro contains 8 values instead of 4,
overflowing into the subsequent fields in the register, and thus breaking
the configuration of the latter.

Fix this by dropping the bogus last 4 values, including the non-existent
SEL_I2C1_4 configuration.

Fixes: 6d4036a1 ("pinctrl: sh-pfc: Initial R8A77990 PFC support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>