bnxt_en: fix HWRM error when querying VF temperature

Firmware returns RESOURCE_ACCESS_DENIED for HWRM_TEMP_MONITORY_QUERY for
VFs. This produces unpleasing error messages in the log when temp1_input
is queried via the hwmon sysfs interface from a VF.

The error is harmless and expected, so silence it and return unknown as
the value. Since the device temperature is not particularly sensitive
information, provide flexibility to change this policy in future by
silencing the error rather than avoiding the HWRM call entirely for VFs.

Fixes: cde49a42 ("bnxt_en: Add hwmon sysfs support to read temperature")
Cc: Marc Smith <msmith626@gmail.com>
Reported-by: Marc Smith <msmith626@gmail.com>
Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>