staging: vchiq_core: improve readability of request_poll

Storing the index for poll services in a local var will increase the
readability of the second loop. Also we get the rid off the checkpatch
issue about the line ending with a square bracket.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://lore.kernel.org/r/1618164700-21150-7-git-send-email-stefan.wahren@i2se.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>