bnxt_en: Free context memory after disabling PCI in probe error path.

Other shutdown code paths will always disable PCI first to shutdown DMA
before freeing context memory.  Do the same sequence in the error path
of probe to be safe and consistent.

Fixes: c20dc142 ("bnxt_en: Disable bus master during PCI shutdown and driver unload.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>