fixed chained derivedfrom in NXP svds

[Jegeva]

linked to issue #96

this fixes the daisy chaining of derivedFrom in the data but doesn't fix the underlying issue.

[posborne]

In general, we do not patch the SVD files themselves here but use them directly from vendors. If we believe there is a problem with the library that's where we should try to find a patch. If you can recreate the failure in a unit test that would be a good first step.

[Jegeva]

@posborne

here you go :

#! /usr/bin/python3
import sys

sys.path = ["./cmsis-svd/python/"] + sys.path
import cmsis_svd
from cmsis_svd.parser import SVDParser
parser = SVDParser.for_packaged_svd('NXP', 'LPC178x_7x' + '.svd')
for p in parser.get_device().peripherals:
    for r in p.registers:
            rname = r.name

This is just recreating the crash, i'll look into the test file