initial builds of OSK5912 boards need srst_pulls_trst

This is clearly noted in the hardware spec (section 5.2.3); it
works around a chip erratum:  "If the MPU_RESET signal is used,
it may cause the EMIFS bus to lock."

I seem to have a board with such an initial build.  The chip
is labeled XOMAP.  Presumably, parts without that "X" prefix
(eXperimental) resolve this.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>