drm: limit to INT_MAX in create_blob ioctl

The hardened usercpy code is too paranoid ever since:

commit 6a30afa8c1fbde5f10f9c584c2992aa3c7f7a8fe
Author: Kees Cook <keescook@chromium.org>
Date:   Wed Nov 6 16:07:01 2019 +1100

    uaccess: disallow > INT_MAX copy sizes

Code itself should have been fine as-is.

Link: http://lkml.kernel.org/r/20191106164755.31478-1-daniel.vetter@ffwll.ch


Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reported-by:  <syzbot+fb77e97ebf0612ee6914@syzkaller.appspotmail.com>
Fixes: 6a30afa8c1fb ("uaccess: disallow > INT_MAX copy sizes")
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>