ARM: dts: r8a7740, emev2, sh73a0: Include SoC name in DTSI

Update the R-Mobile A1 (r8a7740), Emma Mobile EV2 (emev2) and
SH-Mobile AG5 (sh72a0) DTSI to include product name.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
[simon: squashed similar patches]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>