da850evm: fix linux bootparam address

da850evm: fix linux bootparam address

This patch fixes the LINUX_BOOT_PARAM_ADDR define to be based off of
PHYS_SDRAM_1 instead of CONFIG_SYS_MEMTEST_START. On da830 they are the same
thing but on da850 the CONFIG_SYS_MEMSTART define is offset from the
PHYS_SDRAM_1 start.

Without this patch it is not possible to boot linux on da850 -- bootm hangs
at "Uncompressing Linux... done, booting the kernel."

Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>