[SCSI] libsas: better error handling in sas_expander.c
[SCSI] libsas: better error handling in sas_expander.c

With async scanning, we're now tripping the BUG_ON in
sas_ex_discover_end_dev(), so make the error handling here correct.

Signed-off-by: James Bottomley <407b36959ca09543ccda8f8e06721c791bc53435@SteelEye.com>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs