qlge: call ql_core_dump() only if dump memory was allocated.

Also changed a log message to indicate that memory was not allocated
instead of memory not available!

Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
Acked-by: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>