HSI: ssi_protocol: fix struct members kernel-doc warnings

HSI: ssi_protocol: fix struct members kernel-doc warnings

Fix a typo in one struct member's name and add the @work struct member
to quieten kernel-doc warnings:

ssi_protocol.c:144: warning: Function parameter or struct member 'work' not described in 'ssi_protocol'
ssi_protocol.c:144: warning: Function parameter or struct member 'tx_usecnt' not described in 'ssi_protocol'
ssi_protocol.c:144: warning: Excess struct member 'tx_usecount' description in 'ssi_protocol'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20240221064112.9155-1-rdunlap@infradead.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>