board: phytec: phycore_imx8mm: Update lpddr4_timing

Update RAM Timings for 2GB RAM based on DDR Controller Configuration
Spreadsheet revision 22. Including the update of the refresh
rate to workaround errata ERR050805.

Signed-off-by: Cem Tenruh <c.tenruh@phytec.de>
1 file changed