fs/ioctl: remove unnecessary __user annotation

fs/ioctl: remove unnecessary __user annotation

__user annotations are used by the checker (e.g sparse) to mark user
pointers.  However here __user is applied to a struct directly, without a
pointer being directly involved.

Although the presence of __user does not cause sparse to emit a warning,
__user should be removed for consistency with other uses of offsetof().

Note: No functional changes intended.

Link: https://lkml.kernel.org/r/20211122101256.7875-1-amit.kachhap@arm.com
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Cc: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Cc: Kevin Brodsky <Kevin.Brodsky@arm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>