ARM: shmobile: r8a7791: Correct SDHI clock labels and output-names

There appears to have been some inconsistency and confusion here as on
the r8a7790 these clocks are referred to as SD(HI)1 and SD(HI)2 while on
the r8a7791 and r8a7794 they are referred to as SD(HI)2 and SD(HI)3.

Fixes: 59e79895

 ("ARM: shmobile: r8a7791: Add clocks")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>