firmware: Remove obsolete Chelsio cxgb3 firmware

firmware: Remove obsolete Chelsio cxgb3 firmware

The current firmware version used by the device driver
is 7.12.0

Cc: Paul Gortmaker <[email protected]>
Cc: Ben Hutchings <[email protected]>
Cc: James Bottomley <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Divy Le Ray <[email protected]>
Cc: [email protected]
Signed-off-by: Tim Gardner <[email protected]>