ARM: mach-tegra: rearrange SPL configs

SPL configs are used only by the ARMv7-based Tegra SOC's, so move
SPL_SYSRESET under TEGRA_ARMV7_COMMON selection and enable SPL_DM
since SPL_SYSRESET depends on it.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>