cxl/cdat: Free correct buffer on checksum error

cxl/cdat: Free correct buffer on checksum error

The new 6.7-rc1 kernel now checks the checksum on CDAT data.  While
using a branch of Fan's DCD qemu work (and specifying DCD devices), the
following splat was observed.

	WARNING: CPU: 1 PID: 1384 at drivers/base/devres.c:1064 devm_kfree+0x4f/0x60
	...
	RIP: 0010:devm_kfree+0x4f/0x60
	...
 	? devm_kfree+0x4f/0x60
 	read_cdat_data+0x1a0/0x2a0 [cxl_core]
 	cxl_port_probe+0xdf/0x200 [cxl_port]
	...

The issue in qemu is still unknown but the spat is a straight forward
bug in the CDAT checksum processing code.  Use a CDAT buffer variable to
ensure the devm_free() works correctly on error.

Fixes: 670e4e88f3b1 ("cxl: Add checksum verification to CDAT from CXL")
Signed-off-by: Ira Weiny <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Reviewed-by: Fan Ni <[email protected]>
Reviewed-by: Robert Richter <[email protected]>
Link: http://lore.kernel.org/r/[email protected]
Signed-off-by: Dan Williams <[email protected]>