microblaze: Fix bd_info pointer

microblaze: Fix bd_info pointer

Patch "Replace CONFIG_SYS_GBL_DATA_SIZE by auto-generated value"
(sha1: 25ddd1fb0a2281b182529afbc8fda5de2dc16d96)
introduce GENERATED_GBL_DATA_SIZE which is sizeof aligned gd_t
(currently 0x40).
Microblaze configs used 0x40(128) because this place also contained
board info structure which lies on the top of ram.

U-Boot is placed to the top of the ram (for example 0xd7ffffff)
and bd structure was moved out of ram.

This patch is fixing this scheme with GENERATED_BD_INFO_SIZE
which swap global data and board info structures.

For example:
Current: gd 0xd7ffffc0, bd 0xd8000000
Fixed:   gd 0xd7ffffc0, bd 0xd7ffff90

Signed-off-by: Michal Simek <monstr@monstr.eu>