firmware: google: memconsole: Use devm_memremap()

Use the devm version of memremap so that we can delete the unmapping
code in driver remove, but more importantly so that we can unmap this
memory region if memconsole_sysfs_init() errors out for some reason.

Cc: Wei-Ning Huang <wnhuang@chromium.org>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Samuel Holland <samuel@sholland.org>
Cc: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/firmware/google/memconsole-coreboot.c

@@ -85,13 +85,13 @@ static int memconsole_probe(struct coreboot_device *dev)
 
 	/* Read size only once to prevent overrun attack through /dev/mem. */
 	cbmem_console_size = tmp_cbmc->size_dont_access_after_boot;
-	cbmem_console = memremap(dev->cbmem_ref.cbmem_addr,
+	cbmem_console = devm_memremap(&dev->dev, dev->cbmem_ref.cbmem_addr,
 				 cbmem_console_size + sizeof(*cbmem_console),
 				 MEMREMAP_WB);
 	memunmap(tmp_cbmc);
 
-	if (!cbmem_console)
-		return -ENOMEM;
+	if (IS_ERR(cbmem_console))
+		return PTR_ERR(cbmem_console);
 
 	memconsole_setup(memconsole_coreboot_read);
 
@@ -102,9 +102,6 @@ static int memconsole_remove(struct coreboot_device *dev)
 {
 	memconsole_exit();
 
-	if (cbmem_console)
-		memunmap(cbmem_console);
-
 	return 0;
 }