Add MIMXRT1176 MCU description and fix build failure

[multiplemonomials]

Summary of changes

MIMXRT1170_EVK greentea build was failing because there were no memory banks defined for MIMXRT1176. This was actually pretty tough to figure out, even for me who has experience with the MIMRT family of chips, because the CMSIS pack memory description is not too helpful and the datasheet is confusing AF. Finally had to check what the default configuration was in MCUXpresso IDE and that helped a lot.

Impact of changes

MIMXRT1176 MCU now has memory bank information.

Migration actions required

Documentation

See comments in file

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Pull request type

[] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[X] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[X] No Tests required for this change (E.g docs only update)
[] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

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