[SCSI] fusion - bug fix stack overflow in mptbase

Bug fix for stack overflow in EventDescriptionStr, (a function
for debuging firmware events).  We allocated 50 bytes on local stack
for buff[], however there are places in the code where we've attempted
copying in greater than 50 bytes into buff[].

Signed-off-by: Eric Moore <Eric.Moore@lsil.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>