updates for Fuji XT1

[mpeex]

1. updated constants tables to reflect Fuji Xt-1 firmware version 5.52:

Exposure Time             (500d rw u32): Enumeration [244,307,387,488,615,775,976,1230,1550,1953,2460,3100,3906,4921,5524,6200,7812,9843,12401,15625,19686,24803,31250,39372,49606,62500,78745,99212,125000,157490,198425,250000,314980,396850,500000,629960,793700,1000000,1259921,1414213,2000000,2519842,3174802,4000000,5039684,6349604,8000000,10079368,12699208,16000000,20158736,25398416,32000000] value: 3.2e+02 sec (32000000)
White Balance             (5005 rw u16): Enumeration [2,4,6,8,32769,32770,32771,32774,32775,32776,32777,32778] value: Automatic (2)
[Unknown Property](fuji action?)        (d208 rw u16): Enumeration [260,512,4,772] value: 772

2. camera_prepare_capture in XT1 is breaking BULB exposition with external shutter, commented out