shader/shader_ir: Amend three comment typos

Given we're in the area, these are three trivial typos that can be
corrected.

src/video_core/shader/shader_ir.h

@@ -391,7 +391,7 @@ private:
     const InternalFlag flag;
 };
 
-/// A predicate register, it can be negated without aditional nodes
+/// A predicate register, it can be negated without additional nodes
 class PredicateNode final {
 public:
     explicit constexpr PredicateNode(Tegra::Shader::Pred index, bool negated)
@@ -626,10 +626,10 @@ private:
     Node GetPredicate(u64 pred, bool negated = false);
     /// Generates a predicate node for an immediate true or false value
     Node GetPredicate(bool immediate);
-    /// Generates a node representing an input atttribute. Keeps track of used attributes.
+    /// Generates a node representing an input attribute. Keeps track of used attributes.
     Node GetInputAttribute(Tegra::Shader::Attribute::Index index, u64 element,
                            const Tegra::Shader::IpaMode& input_mode, Node buffer = {});
-    /// Generates a node representing an output atttribute. Keeps track of used attributes.
+    /// Generates a node representing an output attribute. Keeps track of used attributes.
     Node GetOutputAttribute(Tegra::Shader::Attribute::Index index, u64 element, Node buffer);
     /// Generates a node representing an internal flag
     Node GetInternalFlag(InternalFlag flag, bool negated = false);