PR1960: ERC32_Is_interrupt_masked for ERC32 in erc32.h

The function-like macro ERC32_Is_interrupt_masked defined as:

  (ERC32_MEC.Interrupt_Masked & (1 << (_source)))

The ERC32_MEC is of type ERC32_Register_Map structure and Interrupt_Masked does
not exist in structure, instead Interrupt_Mask exists.
Update the macro accordingly.