microblaze: switch to NO_BOOTMEM

microblaze: switch to NO_BOOTMEM

Microblaze doesn't set CONFIG_NO_BOOTMEM and so memblock_virt_alloc()
doesn't work for CONFIG_HAVE_MEMBLOCK && !CONFIG_NO_BOOTMEM.

Similar change was already done by others architectures
"ARM: mm: Remove bootmem code and switch to NO_BOOTMEM"
(sha1: d1708c89d717048602ed49ebdd5238fd29a55d8f)
or
"openrisc: Consolidate setup to use memblock instead of bootmem"
(sha1: f9ff79bda6f35611c404d32709a73194d26eb98f)
or
"parisc: Drop bootmem and switch to memblock"
(sha1: 8b7a056136b88cb1f70f43ba6f99e1d1bd5d255a)
or
"powerpc: Remove bootmem allocator"
(sha1: d414ffae6863f2557c9a7de204de4ee9e4607a6f)
or
"s390/mm: Convert bootmem to memblock"
(sha1: 627b517a9184398ba778cf915d93f8f19c4688de)
or
"sparc64: Convert over to NO_BOOTMEM."
(sha1: 7458c06168c58e0797cd58b47a30b3485ddfa38d)
or
"xtensa: drop sysmem and switch to memblock"
(sha1: 27fa3b761c21a885f7cf8586215b0dacd06edf8a)

Issue was introduced by:
"of/fdt: use memblock_virt_alloc for early alloc"
(sha1: 8afc609efdbd7ed65f1db7c34d9cceea7fee62db)

Signed-off-by: Rob Herring <robh@kernel.org>
Tested-by: Alvaro Gamez Machado <alvaro.gamez@hazent.com>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>