nir/algebraic: Add a mechanism for specifying the bit size of a value

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>

src/compiler/nir/nir_search.h

@@ -40,6 +40,8 @@ typedef enum {
 
 typedef struct {
    nir_search_value_type type;
+
+   unsigned bit_size;
 } nir_search_value;
 
 typedef struct {