ARM: shmobile: r8a7791: Fix the I2C clocks parents in legacy code

All I2C clocks derive from the HP clock, not from the P clock. Fix them.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Wolfram Sang <wsa@sang-engineering.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>