ARM: dts: rza: Add I2C interrupt-names

Add "interrupt-names" properties to the I2C device nodes of the RZ/A1H
and RZ/A2M DTS files, to make it easier to review the interrupt mappings.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/7a073439e37f6672e4809af0a2ee9cd4ac820ec6.1626267422.git.geert+renesas@glider.be