Name the #define guarding compilation of this header
__RENESAS_CLK_DIV6_H__ rather than __SHMOBILE_CLK_DIV6_H__.

This is a follow-up to renaming the directory in which this file lives from
shmobile to renesas which is in turn part of an ongoing process to migrate
from ARCH_SHMOBILE to ARCH_RENESAS the motivation for which being that
RENESAS seems to be a more appropriate name than SHMOBILE for the majority
of Renesas ARM based SoCs.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>