[DOXYGEN] Corrected several typos and incorrect parameters description that Sony's techinical writer found during review.

I got an OK from Eric Christopher to commit doxygen comments without prior code
review upstream.

llvm-svn: 304840
diff --git a/clang/lib/Headers/bmiintrin.h b/clang/lib/Headers/bmiintrin.h
index e590cf8..361e5f7 100644
--- a/clang/lib/Headers/bmiintrin.h
+++ b/clang/lib/Headers/bmiintrin.h
@@ -148,7 +148,7 @@
 }
 
 /// \brief Creates a mask whose bits are set to 1, using bit 0 up to and
-///    including the least siginificant bit that is set to 1 in the source
+///    including the least significant bit that is set to 1 in the source
 ///    operand and returns the result.
 ///
 /// \headerfile <x86intrin.h>
@@ -164,7 +164,7 @@
   return __X ^ (__X - 1);
 }
 
-/// \brief Clears the least siginificant bit that is set to 1 in the source
+/// \brief Clears the least significant bit that is set to 1 in the source
 ///    operand and returns the result.
 ///
 /// \headerfile <x86intrin.h>
@@ -309,7 +309,7 @@
 }
 
 /// \brief Creates a mask whose bits are set to 1, using bit 0 up to and
-///    including the least siginificant bit that is set to 1 in the source
+///    including the least significant bit that is set to 1 in the source
 ///    operand and returns the result.
 ///
 /// \headerfile <x86intrin.h>
@@ -325,7 +325,7 @@
   return __X ^ (__X - 1);
 }
 
-/// \brief Clears the least siginificant bit that is set to 1 in the source
+/// \brief Clears the least significant bit that is set to 1 in the source
 ///    operand and returns the result.
 ///
 /// \headerfile <x86intrin.h>