LoongArch: Select HAVE_ARCH_SECCOMP to use the common SECCOMP menu

LoongArch missed the refactoring made by commit 282a181b

 ("seccomp:
Move config option SECCOMP to arch/Kconfig") because LoongArch was not
mainlined at that time.

The 'depends on PROC_FS' statement is stale as described in that commit.
Select HAVE_ARCH_SECCOMP, and remove the duplicated config entry.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>