ARM: Drop CMDLINE_* dependency on ATAGS

On arm32, the configuration options to specify the kernel command line
type depend on ATAGS.  However, the actual CMDLINE cofiguration option
does not depend on ATAGS, and the code that handles this is not specific
to ATAGS (see drivers/of/fdt.c:early_init_dt_scan_chosen()).

Hence users who desire to override the kernel command line on arm32 must
enable support for ATAGS, even on a pure-DT system.  Other architectures
(arm64, loongarch, microblaze, nios2, powerpc, and riscv) do not impose
such a restriction.

Hence drop the dependency on ATAGS.

Fixes: bd51e2f5 ("ARM: 7506/1: allow for ATAGS to be configured out when DT support is selected")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>