ARM: shmobile: r8a7794: alt: add EEPROM to DTS

Same EEPROM as on Koelsch, et al.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>