soc: q6dspv2: apr: fix client registration refcount

Audio Packet Router (APR) is used by multiple audio services
to communicate between APSS and ADSP. These audio services
registers for service level APR communication (port 0xFFFFFFFF),
or for session level APR communication (using port 0x101 etc.).
The services might choose to call apr_register for any port at
random. The expectation is that the refcounting for the number
of ports registered with APR for any specific service, is handled
irrespective of the order in which registrations are done. The
current logic fails to handle the refcounting when apr_register
is called for 0xFFFFFFFF before other session based ports. Fix
this correctly using the service count (svc_cnt) variable in apr_svc.

CRs-fixed: 2022490
Change-Id: I2fcd1269facf24d509db0d90314e0d2545a2ad67
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>