um: Fix pointer cast

Fix a pointer cast typo introduced in v4.4-rc5 especially visible for
the i386 subarchitecture where it results in a kernel crash.

[ Also removed pointless cast as per Al Viro - Linus ]

Fixes: 8090bfd2 ("um: Fix fpstate handling")
Signed-off-by: NMickaël Salaün <mic@digikod.net>
Cc: Jeff Dike <jdike@addtoit.com>
Acked-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/x86/um/signal.c

@@ -470,7 +470,7 @@ long sys_sigreturn(void)
 	struct sigcontext __user *sc = &frame->sc;
 	int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
 
-	if (copy_from_user(&set.sig[0], (void *)sc->oldmask, sizeof(set.sig[0])) ||
+	if (copy_from_user(&set.sig[0], &sc->oldmask, sizeof(set.sig[0])) ||
 	    copy_from_user(&set.sig[1], frame->extramask, sig_size))
 		goto segfault;