arch: simplify several early memory allocations

There are several early memory allocations in arch/ code that use
memblock_phys_alloc() to allocate memory, convert the returned physical
address to the virtual address and then set the allocated memory to
zero.

Exactly the same behaviour can be achieved simply by calling
memblock_alloc(): it allocates the memory in the same way as
memblock_phys_alloc(), then it performs the phys_to_virt() conversion
and clears the allocated memory.

Replace the longer sequence with a simpler call to memblock_alloc().

Link: http://lkml.kernel.org/r/1546248566-14910-6-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/sparc/mm/init_64.c

@@ -1089,16 +1089,13 @@ static void __init allocate_node_data(int nid)
 	struct pglist_data *p;
 	unsigned long start_pfn, end_pfn;
 #ifdef CONFIG_NEED_MULTIPLE_NODES
-	unsigned long paddr;
 
-	paddr = memblock_phys_alloc_try_nid(sizeof(struct pglist_data),
-					    SMP_CACHE_BYTES, nid);
-	if (!paddr) {
+	NODE_DATA(nid) = memblock_alloc_node(sizeof(struct pglist_data),
+					     SMP_CACHE_BYTES, nid);
+	if (!NODE_DATA(nid)) {
 		prom_printf("Cannot allocate pglist_data for nid[%d]\n", nid);
 		prom_halt();
 	}
-	NODE_DATA(nid) = __va(paddr);
-	memset(NODE_DATA(nid), 0, sizeof(struct pglist_data));
 
 	NODE_DATA(nid)->node_id = nid;
 #endif