ARM: mach-at91: armv7: fix multiple cpu_reset definition when enabling SYSRESET

When SYSRESET is enabled, cpu_reset function is also defined in
sysreset-uclass.c which lead to multiple definitions of this function
since reset.c is build unconditionally. Add a check in Makefile to build
this file only if SYSRESET isn't enabled.
SYSRESET can be enabled when building SYSRESET_PSCI for instance on this
platform.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
diff --git a/arch/arm/mach-at91/armv7/Makefile b/arch/arm/mach-at91/armv7/Makefile
index f5b2665..246050b 100644
--- a/arch/arm/mach-at91/armv7/Makefile
+++ b/arch/arm/mach-at91/armv7/Makefile
@@ -11,7 +11,9 @@
 obj-$(CONFIG_SAMA5D4)	+= sama5d4_devices.o clock.o
 obj-$(CONFIG_SAMA7G5)	+= sama7g5_devices.o
 obj-y += cpu.o
-obj-y += reset.o
+ifndef CONFIG_$(SPL_TPL_)SYSRESET
+obj-y	+= reset.o
+endif
 ifneq ($(CONFIG_ATMEL_PIT_TIMER),y)
 ifneq ($(CONFIG_MCHP_PIT64B_TIMER),y)
 # old non-DM timer driver