ARM: rmobile: Remove duplicate configs by Kconfig in rcar-gen3-common.h

This commit remove dupilicate following configs from rcar-gen3-common.h.
  - CONFIG_CMD_BOOTZ
  - CONFIG_BOOTDELAY
  - CONFIG_CMD_EDITENV
  - CONFIG_CMD_SAVEENV
  - CONFIG_CMD_MEMORY
  - CONFIG_CMD_RUN
  - CONFIG_CMD_LOADS

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>