cxgb3: fixing gcc 4.4 compiler warning: suggest parentheses around operand of ‘!’

Trivial: fixing gcc 4.4 compiler warning:
drivers/net/cxgb3/t3_hw.c: In function ‘t3_prep_adapter’:
drivers/net/cxgb3/t3_hw.c:3782: warning: suggest parentheses around operand of ‘!’ or change ‘|’ to ‘||’ or ‘!’ to ‘~’

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
Signed-off-by: David S. Miller <davem@davemloft.net>