coreboot: Replace all IS_ENABLED(CONFIG_XXX) with CONFIG(XXX)

This patch is a raw application of

 find src/ -type f | xargs sed -i -e 's/IS_ENABLED\s*(CONFIG_/CONFIG(/g'

Change-Id: I6262d6d5c23cabe23c242b4f38d446b74fe16b88
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31774
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/arch/riscv/include/arch/cpu.h

@@ -33,7 +33,7 @@ struct thread;
 struct cpu_info {
 	struct device *cpu;
 	unsigned long index;
-#if IS_ENABLED(CONFIG_COOP_MULTITASKING)
+#if CONFIG(COOP_MULTITASKING)
 	struct thread *thread;
 #endif
 };