pmon: xcvrd corrupted data if module types are changed during runtime

[bluecmd]

On our DS4001, if a module is a CMIS and then replaced with a QSFP28 the transceiver info is corrupted. Restarting pmon fixes this.

Compare:

127.0.0.1:6379[6]> hgetall "TRANSCEIVER_INFO|Ethernet248"
 1) "type"
 2) "QSFP28 or later"
 3) "vendor_rev"
 4) ""
 5) "serial"
 6) "\x02SPTSBP2CLCKS  "
 7) "manufacturer"
 8) "\a"
 9) "model"
10) "INTEL CORP      "
11) "vendor_oui"
12) "00-00-40"
13) "vendor_date"
14) "20  -02-fX \x05\x14"
15) "connector"
16) "Unknown"
17) "encoding"
18) "N/A"
19) "ext_identifier"
20) "Power Class 2 (14.0W Max)"
21) "ext_rateselect_compliance"

with

127.0.0.1:6379[6]> hgetall "TRANSCEIVER_INFO|Ethernet248"
 1) "application_advertisement"
 2) "N/A"
 3) "nominal_bit_rate"
 4) "255"
 5) "serial"
 6) "LHCL183817K8P   "
 7) "cable_type"
 8) "Length(km)"
 9) "ext_rateselect_compliance"
10) "Rate Select Version 2"
11) "vendor_rev"
12) "02"
13) "vendor_date"
14) "2018-09-28 00"
15) "cable_length"
16) "1.0"
17) "model"
18) "SPTSBP2CLCKS    "
19) "vendor_oui"
20) "00-02-b3"
21) "type"
22) "QSFP28 or later"