arm64: dts: renesas: r9a07g044: Add I2C interrupt-names

Add "interrupt-names" properties to the I2C device nodes, to make it
easier to review the interrupt mappings.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/d35ba11bd705e3c728f94ff0414ac6ae1156244f.1626267422.git.geert+renesas@glider.be