ARM: shmobile: r8a7740 legacy: Correct IIC0 parent clock

ARM: shmobile: r8a7740 legacy: Correct IIC0 parent clock

According to the datasheet, the operating clock for IIC0 is the HPP
(RT Peri) clock, not the SUB (Peri) clock. Both clocks run at the same
speed (50 Mhz).

This is consistent with IIC0 being located in the A4R PM domain, and
IIC1 in the A3SP PM domain.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
(cherry picked from commit 4f37828d4d69a46830e0525a065da9847fc7a819)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>