[ARM] S3C24XX: Fix use of CONFIG_S3C24XX_PWM

CONFIG_S3C24XX_PWM was defined in arch/arm/plat-s3c24xx/Kconfig but
not used anywhere else as the corresponding makefile used
CONFIG_HAVE_PWM (selected by CONFIG_S3C24XX_PWM) to compile the PWM
driver.

Change the makefile to use CONFIG_S3C24XX_PWM to compile this driver
to ensure it is only build when needed.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

arch/arm/plat-s3c24xx/Makefile

@@ -29,7 +29,7 @@ obj-$(CONFIG_PM_SIMTEC)		+= pm-simtec.o
 obj-$(CONFIG_PM)		+= pm.o
 obj-$(CONFIG_PM)		+= irq-pm.o
 obj-$(CONFIG_PM)		+= sleep.o
-obj-$(CONFIG_HAVE_PWM)		+= pwm.o
+obj-$(CONFIG_S3C24XX_PWM)	+= pwm.o
 obj-$(CONFIG_S3C2410_CLOCK)	+= s3c2410-clock.o
 obj-$(CONFIG_S3C2410_DMA)	+= dma.o
 obj-$(CONFIG_S3C24XX_ADC)	+= adc.o