[SCSI] aacraid: Correct SMC products in aacraid.txt

Correct a spelling mistake for the SMC product names (replace 'B' with
'R') in the Documentation/scsi/aacraid.txt file. This is a follow-up to
a documentation patch '[PATCH] aacraid: Add SMC and SUN products to
README' submitted and accepted to scsi-misc-2.6 on March 27 2007.

Signed-off-by: Mark Salyzyn <aacraid@adaptec.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>