pwm: add driver for nexell

Changes in relation to FriendlyARM's U-Boot nanopi2-v2016.01:
- Since drivers/pwm/pwm-nexell.c is an adapted version of
  s5p-common/pwm.c an appropriately changed version of s5p-common/pwm.c
  is used instead. Therefore arch/arm/mach-s5pc1xx/include/mach/pwm.h
  copied to arch/arm/mach-nexell/include/mach and s5p-common/Makefile
  changed appropriately.
- '#ifdef CONFIG...' changed to 'if (IS_ENABLED(CONFIG...))' where
  possible (and similar).

Signed-off-by: Stefan Bosch <stefan_b@posteo.net>
diff --git a/arch/arm/cpu/armv7/s5p-common/Makefile b/arch/arm/cpu/armv7/s5p-common/Makefile
index 12cf804..bfe0238 100644
--- a/arch/arm/cpu/armv7/s5p-common/Makefile
+++ b/arch/arm/cpu/armv7/s5p-common/Makefile
@@ -3,9 +3,14 @@
 # Copyright (C) 2009 Samsung Electronics
 # Minkyu Kang <mk7.kang@samsung.com>
 
-obj-y		+= cpu_info.o
+ifdef CONFIG_ARCH_NEXELL
+obj-$(CONFIG_PWM_NX) += pwm.o
+obj-$(CONFIG_S5P4418_ONEWIRE) += pwm.o
+else
+obj-y += cpu_info.o
 ifndef CONFIG_SPL_BUILD
-obj-y		+= timer.o
-obj-y		+= sromc.o
-obj-$(CONFIG_PWM)	+= pwm.o
+obj-y += timer.o
+obj-y += sromc.o
+obj-$(CONFIG_PWM) += pwm.o
+endif
 endif