ARM: shmobile: Hide ARCH_RZN1 to improve consistency

Unlike all other family-specific Kconfig symbols for Renesas ARM SoCs,
ARCH_RZN1 is user-visible.  As this symbol is already selected by the
SoC-specific ARCH_R9A06G032 symbol, there is no need for that.

Hide ARCH_RZN1 from the user, and move it up, where all other
family-specific Kconfig symbols live.  Drop the select of CPU_V7, as
this is already implied by the dependency of ARCH_RENESAS on
ARCH_MULTI_V7.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>