staging: unisys: visorbus: replaced vague 'p' variable with 'pos'

In the case of client_bus_info_show, the variable 'p' was used to
indicate the position in the output buffer. This was changed to 'pos' to
indicate that it kept track of the current position in the output
buffer.

Signed-off-by: Alexander Curtin <alexander.curtin@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>