rv: remove redundant initialization of pointer ptr

The pointer ptr is being initialized with a value that is never read,
it is being updated later on a call to strim. Remove the extraneous
initialization.

Link: https://lkml.kernel.org/r/20230116161612.77192-1-colin.i.king@gmail.com

Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>