cdx: remove unused struct 'cdx_mcdi_copy_buffer'

'cdx_mcdi_copy_buffer' has been unused since the original
commit eb96b74 ("cdx: add MCDI protocol interface for firmware
interaction").

Looking at lkml,  it was used in the V1 posting but was removed
somewhere before V6.

Remove it.

Signed-off-by: Dr. David Alan Gilbert <[email protected]>
Acked-by: Nipun Gupta <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Dr. David Alan Gilbert

drivers/cdx/controller/mcdi.c

@@ -27,10 +27,6 @@
 #include "bitfield.h"
 #include "mcdi.h"
 
-struct cdx_mcdi_copy_buffer {
-	struct cdx_dword buffer[DIV_ROUND_UP(MCDI_CTL_SDU_LEN_MAX, 4)];
-};
-
 static void cdx_mcdi_cancel_cmd(struct cdx_mcdi *cdx, struct cdx_mcdi_cmd *cmd);
 static void cdx_mcdi_wait_for_cleanup(struct cdx_mcdi *cdx);
 static int cdx_mcdi_rpc_async_internal(struct cdx_mcdi *cdx,