bug fix about ISOfilesystem and sceIo

1: when open a file "umd1:/sce_lbn0x0_size0x6B49D200",  it means open umd1 as block device, the params of sceIoLseek/sceIoRead is LBA mode. 

2: whhen sceIoread return value less than 100, (result/100) is 0. this cause a running thread stay in ready list.