Fixes for Issues #s 2105 and 2106.

Fixes for Issues #s 2105 and 2106.

For issue 2105 after more analysis there might be a very rare situation
(since this is not hit by the tests we have in coreclr and corefx) where
(even though there are not XMM callee saved register on System V) a
circular dependency might occur when homing params passed in XMM
registers. Used the right instruction for doing copying of XMM reg to XMM
reg

For issue # 2106 make sure for 2 register passed struct to use the
already available scOtherReg in struct psiScope.