IntegerFunctions2INTEL has extra dependency on Shader

[bashbaug]

According to the SPV_INTEL_shader_integer_functions2 specification, the IntegerFunctions2INTEL capability added by this extension should not depend on any other capabilities, but in the SPIR-V grammar file there is an implicit dependency on Shader:

SPIRV-Headers/include/spirv/unified1/spirv.core.grammar.json

Lines 16315 to 16321 in 2b2e05e

	{
	"enumerant" : "IntegerFunctions2INTEL",
	"value" : 5584,
	"capabilities" : [ "Shader" ],
	"extensions" : [ "SPV_INTEL_shader_integer_functions2" ],
	"version" : "None"
	},

We should fix this inconsistency. Because I don't see anything in the descriptions of these instructions that would make them Shader specific I would prefer to update the grammar file vs. updating the spec, but either is possible.

CC: @ianromanick