hexagon: Remove CONFIG_HEXAGON_ARCH_VERSION from uapi header

uapi headers should not expose CONFIG switches since they are not
available in userspace. Fix it in arch/hexagon/include/uapi/asm/user.h
by always defining the cs0 and cs1 entries instead of pad values.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>