Documentation: Remove ZBOOT MMC/SDHI utility and docs

Remove ZBOOT MMC/SDHI Documentation for sh7372 together
wit the vrl4 utility. Without sh7372 and Mackerel support
these files are no longer useful.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
diff --git a/Documentation/Makefile b/Documentation/Makefile
index 6883a1b..bc05482 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -1,4 +1,4 @@
-subdir-y := accounting arm auxdisplay blackfin connector \
+subdir-y := accounting auxdisplay blackfin connector \
 	filesystems filesystems ia64 laptops mic misc-devices \
 	networking pcmcia prctl ptp spi timers vDSO video4linux \
 	watchdog