of/fdt: Populate phys_initrd_start/phys_initrd_size from FDT

Now that we have central and global variables holding the physical
address and size of the initrd, we can have
early_init_dt_check_for_initrd() populate
phys_initrd_start/phys_initrd_size for us.

This allows us to remove a chunk of code from arch/arm/mm/init.c
introduced with commit 65939301ac ("arm: set initrd_start/initrd_end
for fdt scan").

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/fdt.c

@@ -924,6 +924,8 @@ static void __init early_init_dt_check_for_initrd(unsigned long node)
 	end = of_read_number(prop, len/4);
 
 	__early_init_dt_declare_initrd(start, end);
+	phys_initrd_start = start;
+	phys_initrd_size = end - start;
 
 	pr_debug("initrd_start=0x%llx  initrd_end=0x%llx\n",
 		 (unsigned long long)start, (unsigned long long)end);