sata: ahsata: Fix wrong operand for checking SERR DIAG_X

Fix coverity issue CID 3261683: Wrong operator used
(CONSTANT_EXPRESSION_RESULT) operator_confusion:
({...; __v;}) | 67108864 is always 1/true regardless of the values
of its operand. This occurs as the logical operand of !

When DIAG_X is set, the PHY COMINIT signal is detected, so
should use '&' to check whether it is set.

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Simon Glass <sjg@chromium.org>