The unittest dtbs have various intentional errors which cause warnings.
With the latest dtc sync to v1.6.1-19-g0a3a9d3449c8, we need to disable
some new checks: node_name_vs_property_name and interrupt_map warnings.
These warnings are also generated for static_base_1.dtb, so add
DTC_FLAGS for it.

Note that the interrupt_map warnings only appear once interrupt_provider
warning is re-enabled globally.

drivers/of/unittest-data/tests-interrupts.dtsi:32.26-35.6: Warning (interrupt_map): /testcase-data/interrupts/intmap1: Missing '#address-cells' in interrupt-map provider

Fixes: c12632bfb611 ("scripts/dtc: Update to upstream version v1.6.1-19-g0a3a9d3449c8")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Frank Rowand <frowand.list@gmail.com>
Tested-by: Frank Rowand <frowand.list@gmail.com>
Link: https://lore.kernel.org/r/20211028130423.4025578-1-robh@kernel.org/Signed-off-by: Rob Herring <robh@kernel.org>