The cache functions to flush user cache (*_flush_user_cache_all)
are in many cases just a branch to the corresponfing userspace or
kernelspace function. These functions also have the same arguments.

Simplify these by using SYM_FUNC_ALIAS() in all affected sites.

The NOP cache has very many similar calls which are just returns,
but it would be confusing to use aliases here, so leave all the
explicit returns and drop a comment on why we are not using aliases.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>