net: wwan: t7xx: Fix the ACPI memory leak

The ACPI buffer memory (buffer.pointer) should be freed as the
buffer is not used after acpi_evaluate_object(), free it to
prevent memory leak.

Fixes: 13e920d93e37 ("net: wwan: t7xx: Add core components")
Signed-off-by: Hanjun Guo <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/wwan/t7xx/t7xx_modem_ops.c

···
 		return -EFAULT;
 	}
 
+	kfree(buffer.pointer);
+
 #endif
 	return 0;
 }