ieee1275: no-data-command bus specific method

IEEE 1275-1994 Standard for Boot (Initialization Configuration)
Firmware: Core Requirements and Practices

E.3.2.2 Bus-specific methods for bus nodes

A package implementing the scsi-2 device type shall implement the
following bus-specific method:

no-data-command ( cmd-addr -- error? )
Executes a simple SCSI command, automatically retrying under
certain conditions.  cmd-addr is the address of a 6-byte command buffer
containing an SCSI command that does not have a data transfer phase.
Executes the command, retrying indefinitely with the same retry criteria
as retry-command.

error? is nonzero if an error occurred, zero otherwise.
NOTE no-data-command is a convenience function. It provides
no capabilities that are not present in retry-command, but for
those commands that meet its restrictions, it is easier to use.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

include/grub/ieee1275/ieee1275.h

@@ -213,6 +213,9 @@ int EXPORT_FUNC(grub_ieee1275_milliseconds) (grub_uint32_t *msecs);
 int EXPORT_FUNC(grub_ieee1275_set_address) (grub_ieee1275_ihandle_t ihandle,
                                             grub_uint32_t target,
                                             grub_uint32_t lun);
+int EXPORT_FUNC(grub_ieee1275_no_data_command) (grub_ieee1275_ihandle_t ihandle,
+                                                const void *cmd_addr,
+                                                grub_ssize_t *result);
 int EXPORT_FUNC(grub_ieee1275_decode_unit4) (grub_ieee1275_ihandle_t ihandle,
                                              void *addr, grub_size_t size,
                                              grub_uint32_t *phy_lo,