mmc: card: Don't show eMMC RPMB and BOOT areas in /proc/partitions

Since RPMB area is accessible via special ioctl only and boot areas
are unlikely to contain any partitions, exclude them all from listing
in /proc/partitions. This will hide them from various user-level
software (e.g. fdisk), thus avoiding unnecessary access attempts.

Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Signed-off-by: Harish Jenny K N <harish_kandiga@mentor.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>