update xcu.yaml with new focus positions

After SMx AIT work (i.e. SM2andSM4 integration and VPHG rotation) focus position was measured for each camera. Update pfs_instdata with new position. 

• xcu_b1 motors moveCcd a=161.71 b=164.31 c=113.14 microns abs
• xcu_r1 motors moveCcd a=177.21 b=179.43 c=143.81 microns abs
• (n1: under analysis, but image quality looks OK with the current position)
• xcu_b3 motors moveCcd a=227.99 b=218.49 c=210.54 microns abs
• xcu_r3 motors moveCcd a=210.83 b=198.18 c=196.71 microns abs
  • cf) second measurement to confirm xcu_r3 motors moveCcd a=208.78 b=195.47 c=196.21 microns abs
• (n3: under analysis, but image quality looks OK with the current position)

fmadec measured SM2/SM4

• xcu_b2 motors moveCcd a=217.30 b=236.64 c=204.88 microns abs
• xcu_r2 motors moveCcd a=161.86 b=191.76 c=157.80 microns abs
• (n2: under analysis, but image quality looks OK)
• xcu_b4 motors moveCcd a=116.00 b=93.56 c=108.95 microns abs
• xcu_r4 motors moveCcd a=107.57 b=67.37 c=89.13 microns abs