samsung-i930{0,5}: fix so that device can boot again

Fixes #1156 (closed). Turns out issue was with the dtb variables in the deviceinfo file (introduced in 69cd6ff8), and not the CMDLINE or the flash offset base.

Also change the CMDLINE that is specified in the kernel config while we are at it, the previous one is based on the generic exynos_defconfig, but the values do not really seem to be applicable for the exynos4 devices or pmos.