MdePkg SafeIntLib: Update API definition to use the same output name
MdePkg SafeIntLib: Update API definition to use the same output name

In SafeUintnToChar8(), update its output parameter name.
Update pui8Result --> Result to match its library implementation

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>
Reviewed-by: Michael Kinney <fd20bc543a9f65bb633fac7d08a403c1f1c8eb6c@intel.com>
Reviewed-by: Laszlo Ersek <7437296077edea1cb64451c122c4dac071f0cfbc@redhat.com>

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2