drivers: convert makefiles to Kbuild style

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile
index 4457a78..4b8cbec 100644
--- a/drivers/tpm/Makefile
+++ b/drivers/tpm/Makefile
@@ -3,31 +3,10 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-include $(TOPDIR)/config.mk
-
-LIB := $(obj)libtpm.o
-
 $(shell mkdir -p $(obj)slb9635_i2c)
 
 # TODO: Merge tpm_tis_lpc.c with tpm.c
-COBJS-$(CONFIG_TPM_ATMEL_TWI) += tpm_atmel_twi.o
-COBJS-$(CONFIG_TPM_TIS_I2C) += tpm.o
-COBJS-$(CONFIG_TPM_TIS_I2C) += tpm_tis_i2c.o
-COBJS-$(CONFIG_TPM_TIS_LPC) += tpm_tis_lpc.o
-
-COBJS	:= $(COBJS-y)
-SRCS	:= $(COBJS:.o=.c)
-OBJS	:= $(addprefix $(obj),$(COBJS))
-
-all:	$(LIB)
-
-$(LIB): $(obj).depend $(OBJS)
-	$(call cmd_link_o_target, $(OBJS))
-
-#########################################################################
-
-include $(SRCTREE)/rules.mk
-
-sinclude $(obj).depend
-
-#########################################################################
+obj-$(CONFIG_TPM_ATMEL_TWI) += tpm_atmel_twi.o
+obj-$(CONFIG_TPM_TIS_I2C) += tpm.o
+obj-$(CONFIG_TPM_TIS_I2C) += tpm_tis_i2c.o
+obj-$(CONFIG_TPM_TIS_LPC) += tpm_tis_lpc.o