input: Convert i8042 to driver model

Adjust this driver to support driver model. The only users are x86 boards
so this should be safe.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/input/Makefile b/drivers/input/Makefile
index 9388dfe..5f15265 100644
--- a/drivers/input/Makefile
+++ b/drivers/input/Makefile
@@ -7,7 +7,7 @@
 
 obj-$(CONFIG_DM_KEYBOARD) += keyboard-uclass.o
 
-obj-$(CONFIG_I8042_KBD) += i8042.o
+obj-$(CONFIG_I8042_KEYB) += i8042.o
 obj-$(CONFIG_TEGRA_KEYBOARD) += tegra-kbc.o
 obj-$(CONFIG_TWL4030_INPUT) += twl4030.o
 obj-$(CONFIG_CROS_EC_KEYB) += cros_ec_keyb.o