MIPS: asm: syscall: Fix copying system call arguments

MIPS: asm: syscall: Fix copying system call arguments

The syscall_get_arguments function expects the arguments to be copied
to the '*args' argument but instead a local variable was used to hold
the system call argument. As a result of which, this variable was
never passed to the filter and any filter testing the system call
arguments would fail. This is fixed by passing the '*args' variable
as the destination memory for the system call arguments.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Reviewed-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6402/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>