dt-bindings: add MYIR Tech hardware vendor prefix

MYIR Tech Limited offers a range of ARM powered development boards and SoMs,
for details reference a list on http://elinux.org/Development_Platforms#ARM
or company's website http://myirtech.com



Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Rob Herring <robh@kernel.org>