intel: common: Improve mailbox driver readability

Use pre-defined macros for return values and common mailbox arguments

Signed-off-by: Abdul Halim, Muhammad Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I5d549ee5358aebadf909f79fda55e83ee9844a0e
3 files changed