[U-Boot] nand_bbt: Out of memory for large block NAND

[J.C. Wren]

The NAND bad block code is throwing an error at startup of 'nand_bbt: Out of
memory' for large block NAND flash (block size of 128K).
The vmalloc() call is trying to allocate 135,168 bytes.
CONFIG_SYS_MALLOC_LEN is (0x10000 + 128*1024).

Bumping CONFIG_SYS_MALLOC_LEN to (0x20000 + 128*1024) wasn't sufficient,
however (0x40000 + 128*1024) was.

Any recommendations what this should be adjusted to? The system has 256MB of
RAM and a single 512MB NAND.

--jc