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/c6x/mm/dma-coherent.c

@@ -121,8 +121,6 @@ void arch_dma_free(struct device *dev, size_t size, void *vaddr,
  */
 void __init coherent_mem_init(phys_addr_t start, u32 size)
 {
-	phys_addr_t bitmap_phys;
-
 	if (!size)
 		return;
 
@@ -138,11 +136,8 @@ void __init coherent_mem_init(phys_addr_t start, u32 size)
 	if (dma_size & (PAGE_SIZE - 1))
 		++dma_pages;
 
-	bitmap_phys = memblock_phys_alloc(BITS_TO_LONGS(dma_pages) * sizeof(long),
-					  sizeof(long));
-
-	dma_bitmap = phys_to_virt(bitmap_phys);
-	memset(dma_bitmap, 0, dma_pages * PAGE_SIZE);
+	dma_bitmap = memblock_alloc(BITS_TO_LONGS(dma_pages) * sizeof(long),
+				    sizeof(long));
 }
 
 static void c6x_dma_sync(struct device *dev, phys_addr_t paddr, size_t size,