scsi: myrs: Fix crash in error case

In the Linux kernel, the following vulnerability has been resolved:

scsi: myrs: Fix crash in error case

In myrs_detect(), cs->disable_intr is NULL when privdata->hw_init() fails

with non-zero. In this case, myrs_cleanup(cs) will call a NULL ptr and

crash the kernel.

[ 1.105606] myrs 0000:00:03.0: Unknown Initialization Error 5A

[ 1.105872] myrs 0000:00:03.0: Failed to initialize Controller

[ 1.106082] BUG: kernel NULL pointer dereference, address: 0000000000000000

[ 1.110774] Call Trace:

[ 1.110950] myrs_cleanup+0xe4/0x150 [myrs]

[ 1.111135] myrs_probe.cold+0x91/0x56a [myrs]

[ 1.111302] ? DAC960_GEM_intr_handler+0x1f0/0x1f0 [myrs]

[ 1.111500] local_pci_probe+0x48/0x90