It's not a big deal really, neither was Valencia's reaction. Just one of those things and I doubt either side will spend much time over it.
I'd disagree, in that whilst it's a friendly there are things both players can learn from this.
Firstly, Valencia trying to throttle Raheem shows he needs to calm down some as regardless of the tackle you can't/shouldn't do that.
Secondly, we all remember Stevie was a card magnet when he first started as he would dive in too much and try too hard to influence things. Raheem was trying to make up for an error and dived in when he didn't need to. To use the cliché, if he stays on his feet and either makes a tackle or shepherds Valencia out of play then it's a much better result. As he grows up, he'll become wiser and make better decisions on when to dive in and when not to do so.
A well executed sliding tackle always looks good but a standing tackle shows better awareness and skill, and allows for a quicker counter-attack.