staging: iio: gyro: Remove & on function name to conform to similar IIO drivers

Remove & from function pointers to conform to the style preferred in IIO.
(Note that this is fine in staging drivers, but would create too much churn
to do outside of staging, unless otherwise working on a driver).

Done using the following semantic patch

// <smpl>
@r@
identifier f;
@@

f(...) { ... }
@@
identifier r.f;
@@

- &f
+ f
// </smpl>

Signed-off-by: simran singhal <singhalsimran0@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>