media: dvb-core: dvb_ringbuffer: Fix various coding style issues

media: dvb-core: dvb_ringbuffer: Fix various coding style issues

The file dvb_ringbuffer.c has several minor coding style violations.
This patch resolves these issues to improve code readability and align
the code with the Linux kernel coding style.

The cleanups include:
- Adding spaces around assignment and comparison operators.
- Adding spaces after commas in function arguments.
- Placing statements on a new line for single-line 'if' blocks.
- Correcting minor indentation.

This is a purely stylistic change with no functional impact.

Signed-off-by: Darshan Rathod <darshanrathod475@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
[hverkuil: split rbuf->pread = rbuf->pwrite = 0 in two lines]