block: uapi: Fix compilation errors using ioprio.h with C++

The use of the "class" argument name in the ioprio_value() inline
function in include/uapi/linux/ioprio.h confuses C++ compilers
resulting in compilation errors such as:

/usr/include/linux/ioprio.h:110:43: error: expected primary-expression before ‘int’
  110 | static __always_inline __u16 ioprio_value(int class, int level, int hint)
      |                                           ^~~

for user C++ programs including linux/ioprio.h.

Avoid these errors by renaming the arguments of the ioprio_value()
function to prioclass, priolevel and priohint. For consistency, the
arguments of the IOPRIO_PRIO_VALUE() and IOPRIO_PRIO_VALUE_HINT() macros
are also renamed in the same manner.

Reported-by: Igor Pylypiv <ipylypiv@google.com>
Fixes: 01584c1e ("scsi: block: Improve ioprio value validity checks")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Tested-by: Igor Pylypiv <ipylypiv@google.com>
Link: https://lore.kernel.org/r/20230814215833.259286-1-dlemoal@kernel.org


Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>