CurieBLE: Correct EIR length calculations

[sandeepmistry]

Fixes #543.

Corrects two things:

1. lengthOfScanRsp was never updated
2. Space calculations where not taking EIR header length (2 bytes) into account

@SidLeung please consider this change for Elnath, if it is too late for Bootes.

cc/ @CarlaMSedze @rodriguezcarlos

[SidLeung]

@russmcinnis , please perform system testing and inform @yashaswini-hanji upon successful completion. Thanks.

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