ARM: shmobile: r8a7791: Remove legacy clock aliases for DT devices

Now that the r8a7791 DT platforms use the common clock framework,
there's no need to manually create clock aliases for devices
instantiated through DT, as those devices will reference their clocks
directly in the device tree. Remove those aliases.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>