wifi: ipw2x00: fix format-truncation warnings

On v6.6-rc4 with GCC 13.2 I see:

drivers/net/wireless/intel/ipw2x00/ipw2100.c:5905:63: warning: '%s' directive output may be truncated writing up to 63 bytes into a region of size 32 [-Wformat-truncation=]
drivers/net/wireless/intel/ipw2x00/ipw2100.c:5905:9: note: 'snprintf' output between 4 and 140 bytes into a destination of size 32
drivers/net/wireless/intel/ipw2x00/ipw2200.c:10392:63: warning: '%s' directive output may be truncated writing up to 63 bytes into a region of size 32 [-Wformat-truncation=]
drivers/net/wireless/intel/ipw2x00/ipw2200.c:10392:9: note: 'snprintf' output between 4 and 98 bytes into a destination of size 32

Fix this by copying only the firmware version and not providing any extra
information via ethtool. This is an ancient driver anyway and most likely
removed soon so it doesn't really matter.

Compile tested only.

Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231012135854.3473332-2-kvalo@kernel.org