passthrough: fix flag for expansion rom base address register.

passthrough: fix flag for expansion rom base address register.

pt_bar_reg_parse() is called for expansion rom base address register.
Currently it returns PT_BAR_FLAG_MEM if bit 0 is 0. It returns
PT_BAR_FLAG_IO if bit 0 is 1.

But bit 0 in expansion rom base address register is enable bit. If bit
0 is 1 for some reason, it returns PT_BAR_FLAG_IO. Expansion rom is
mapped to memory space. It should return PT_BAR_FLAG_MEM.

After applying this patch, it returns PT_BAR_FLAG_MEM regardless
of bit 0, when it is called for expansion rom base address register.

Signed-off-by: Yuji Shimada <shimada-yxb@necst.nec.co.jp>