ravb: Rename "tsrq" variable

Rename the variable "tsrq" with "tccr_mask" as we are passing
TCCR mask to the ravb_wait() function.

There is no functional change.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Suggested-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>