In my opinion, your build could use some improvement. Some of your items just don't seem worth getting on Yorick. This may be just due to a difference in style of play or something. Here are the items I disagree with-

Trinity Force - It's a good, solid item for off-tanking. On Yorick though, it's just meh if you ask me. The attack damage, health, and mana are all good, but not worth spending 4k on. Yorick's abilities all scale rly well with attack damage and health, so you should focus on these two stats. Attack speed and critical strike are simply inferior, which is a good chunk of Trinity Force's stats.

Atma's Impaler - Your only items with health are Trinity Force and Banshee's. Its passive is only going to give you maybe 45 damage, there are better items for armor, and critical strike doesn't help much without plenty of damage and/or an infinity edge. I'm not hating on Atma's on Yorick, I just think you should have a Frozen Mallet or Warmog's or something to go along with it.

Frozen Heart - You already have armor in your build, more isn't really needed. You don't need more mana if you already have a Manamune, it has all you should need. If you still keep running out of mana with a Manamune, you must really be spamming your abilities like there's no tomorrow. The CDR is good, but you can get it in other items such as a Youmuu's (my advice), Spirit Visage, Soul Shroud, or Shurelya's.

What I do like - I'm a big fan of the 0-9-21 mastery tree on him. I completely agree with the 9 masteries you chose for defense too. Your skill sequence is the exact same I use. I also think jungle Yorick is completely viable. I know he can solo dragon very quickly once he's around level 10. I've never actually tried jungling myself, but I'm thinking he could go pretty fast at level 3 and up. He's a pretty good ganker too, not the greatest because his cc isn't that strong, but instasummoning three ghouls on the enemy and charging in is pretty strong nonetheless.

I do disagree with him be a bad laner/squishy early though. I've never had any troubles laning early game with him, you just need to level your E up and use it to keep your health bar high. If you play smart and correctly, he's a very good laner and should usually come out of the laning phase with positive stats.