Linux: Remove ZFS_AC_KERNEL_SRC_MODULE_PARAM_CALL_CONST autotools check

On older kernels, the definition for module_param_call() typecasts
function pointers to (void *), which triggers -Werror, causing the
check to return false when it should return true.

Fixing this breaks the build process on some older kernels because they
define a __check_old_set_param() function in their headers that checks
for a non-constified ->set(). We workaround that through the c
preprocessor by defining __check_old_set_param(set) to (set), which
prevents the build failures.

However, it is now apparent that all kernels that we support have
adopted the GRSecurity change, so there is no need to have an explicit
autotools check for it anymore. We therefore remove the autotools check,
while adding the workaround to our headers for the build time
non-constified ->set() check done by older kernel headers.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #13984
Closes #14004