riscv: Do not overwrite initrd_start and initrd_end

setup_initrd() overwrites initrd_start and initrd_end if __initramfs_size
is larger than 0, which is always true even if there is no embedded
initramfs. This prevents booting qemu with "-initrd" parameter.
Overwriting initrd_start and initrd_end is not necessary since
__initramfs_start and __initramfs_size are used directly in
populate_rootfs() to load the built-in initramfs, so just drop
that code.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/kernel/setup.c

@@ -85,15 +85,8 @@ atomic_t hart_lottery;
 #ifdef CONFIG_BLK_DEV_INITRD
 static void __init setup_initrd(void)
 {
-	extern char __initramfs_start[];
-	extern unsigned long __initramfs_size;
 	unsigned long size;
 
-	if (__initramfs_size > 0) {
-		initrd_start = (unsigned long)(&__initramfs_start);
-		initrd_end = initrd_start + __initramfs_size;
-	}
-
 	if (initrd_start >= initrd_end) {
 		printk(KERN_INFO "initrd not found or empty");
 		goto disable;