85xx: bugfix for reading maximum TLB size on mpc85xx

The MAXSIZE field in the TLB1CFG register is 4 bits, not 8 bits.
This made setup_ddr_tlbs() try to set up a TLB larger than the e500 maximum
(256 MB)
which made u-boot hang in board_init_f() when trying to create a new stack
in RAM.
I have an mpc8540 with one 1GB dimm.

Signed-off-by: Fredrik Arnerup <fredrik.arnerup@edgeware.tv>
Signed-off-by: Andy Fleming <afleming@freescale.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>

cpu/mpc85xx/tlb.c

@@ -134,7 +134,7 @@ unsigned int setup_ddr_tlbs(unsigned int memsize_in_meg)
 	unsigned int tlb_size;
 	unsigned int ram_tlb_index = CONFIG_SYS_DDR_TLB_START;
 	unsigned int ram_tlb_address = (unsigned int)CONFIG_SYS_DDR_SDRAM_BASE;
-	unsigned int max_cam = (mfspr(SPRN_TLB1CFG) >> 16) & 0xff;
+	unsigned int max_cam = (mfspr(SPRN_TLB1CFG) >> 16) & 0xf;
 	u64 size, memsize = (u64)memsize_in_meg << 20;
 
 	size = min(memsize, CONFIG_MAX_MEM_MAPPED);