Both clock-r8a7740.c and clock-r8a7790.c define a div4_clks array as
non-static. Compiling support for both SoCs thus result in a symbol
redefinition. Fix it by defining the arrays as static.

To avoid further similar issues, also define the main_clks as static.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>