Update integration and HW spec

[clayton8]

• Add note about MCU MBOX DLEN 0 SRAM clearing behavior
• Add external staging area strap
• Update SOC usage of generic input/output wires
• Remove FIPS_ZEROIZATION_PPD_i generic input wire usage since port exist on CSS
• Add generic output wire usage table

[Copilot]

Pull Request Overview

This PR updates integration and hardware specification documentation to clarify mailbox behavior and add external staging area configuration. The changes focus on improving clarity around MBOX SRAM clearing behavior when DLEN=0 and documenting the external staging area strap configuration.

• Add clarification about MCU MBOX DLEN 0 SRAM clearing behavior and workaround
• Add external staging area strap configuration parameter
• Update MCI generic input wire allocation guidance

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
docs/CaliptraSSIntegrationSpecification.md	Adds external staging area strap parameter, new MCU mailbox DLEN section, and updates generic wire allocation guidance
docs/CaliptraSSHardwareSpecification.md	Adds note about DLEN=0 causing entire MBOX SRAM clearing

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}