arm64: ptrace: Remove redundant overrun check from compat_vfp_set()

compat_vfp_set() checks for userspace trying to write an excessive
amount of data to the regset.  However this check is conspicuous
for its absence from every other _set() in the arm64 ptrace
implementation.  In fact, the core ptrace_regset() already clamps
userspace's iov_len to the regset size before the individual regset
.{get,set}() methods get called.

This patch removes the redundant check.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/kernel/ptrace.c

@@ -937,9 +937,6 @@ static int compat_vfp_set(struct task_struct *target,
 	compat_ulong_t fpscr;
 	int ret;
 
-	if (pos + count > VFP_STATE_SIZE)
-		return -EIO;
-
 	uregs = &target->thread.fpsimd_state.user_fpsimd;
 
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, uregs, 0,