Refactor ProviderValueAsAscii()

[wenbhou]

Description

Refactor ProviderValueAsAscii() and remove following macros to make it can allocate buffer with right size for each setting.
Fix #43

#define ENABLED_STRING_SIZE                (9)
#define ASSET_TAG_STRING_MAX_SIZE          (22)
#define SECURE_BOOT_ENUM_STRING_SIZE       (20)
#define SYSTEM_PASSWORD_STATE_STRING_SIZE  (30)
#define USB_PORT_STATE_STRING_SIZE         (20)

• Impacts functionality?
  • Functionality - Does the change ultimately impact how firmware functions?
  • Examples: Add a new library, publish a new PPI, update an algorithm, ...
• Impacts security?
  • Security - Does the change have a direct security impact on an application,
    flow, or firmware?
  • Examples: Crypto algorithm change, buffer overflow fix, parameter
    validation improvement, ...
• Breaking change?
  • Breaking change - Will anyone consuming this change experience a break
    in build or boot behavior?
  • Examples: Add a new library class, move a module to a different repo, call
    a function in a new library class in a pre-existing module, ...
• Includes tests?
  • Tests - Does the change include any explicit test code?
  • Examples: Unit tests, integration tests, robot tests, ...
• Includes documentation?
  • Documentation - Does the change contain explicit documentation additions
    outside direct code modifications (and comments)?
  • Examples: Update readme file, add feature readme file, link to documentation
    on an a separate Web page, ...

How This Was Tested

Tested with SEMM tool. No regression seen.

Integration Instructions

N/A

[makubacki]

@wenbhou, it looks like there's just uncrustify errors. Other than those, are you ready for this to be merged?