cdrom: add more GPCMD_* constants

Add GPCMD_* constants for READ_BUFFER, WRITE_12 and WRITE_BUFFER for
completeness.  These will be used libata.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

include/linux/cdrom.h

@@ -451,6 +451,7 @@ struct cdrom_generic_command
 #define GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL  0x1e
 #define GPCMD_READ_10			    0x28
 #define GPCMD_READ_12			    0xa8
+#define GPCMD_READ_BUFFER		    0x3c
 #define GPCMD_READ_BUFFER_CAPACITY	    0x5c
 #define GPCMD_READ_CDVD_CAPACITY	    0x25
 #define GPCMD_READ_CD			    0xbe
@@ -480,7 +481,9 @@ struct cdrom_generic_command
 #define GPCMD_TEST_UNIT_READY		    0x00
 #define GPCMD_VERIFY_10			    0x2f
 #define GPCMD_WRITE_10			    0x2a
+#define GPCMD_WRITE_12			    0xaa
 #define GPCMD_WRITE_AND_VERIFY_10	    0x2e
+#define GPCMD_WRITE_BUFFER		    0x3b
 /* This is listed as optional in ATAPI 2.6, but is (curiously) 
  * missing from Mt. Fuji, Table 57.  It _is_ mentioned in Mt. Fuji
  * Table 377 as an MMC command for SCSi devices though...  Most ATAPI