iio: Remove single use of macro definition for driver name

iio: Remove single use of macro definition for driver name

There is really no reason for having the driver name as a macro
definition if it is only used once (often as `.name` in `struct
device_driver`). It is also more readable this way. Remove these macro
definitions and instead use the string literal directly.

Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Link: https://patch.msgid.link/4840779a167e027b8be77c82f7a4f27210ef084a.1748356671.git.waqar.hameed@axis.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>