MIPS: Loongson64: remove ROM Size unit in boardinfo

Per Appendix A.7 in Q/LS 0013-2014 (龙芯CPU开发系统固件与内核接口规范 V2.2,
lit. Loongson DevSys Firmware Kernel Interface Specification V2.2),
interface_info.size is size of this interface, not size of the LEFI BIOS
ROM.

In any case, the BIOS ROM Size just cannot be several kilobytes (KB) on
Loongson64 LEFI platforms.

Reported-by: Mingcong Bai <jeffbai@aosc.io>
Suggested-by: Icenowy Zheng <uwu@icenowy.me>
Fixes: 6c1bfbd9 ("MIPS: Loongson64: Add /sys/firmware/lefi/boardinfo")
Cc: stable@vger.kernel.org
Signed-off-by: Kexy Biscuit <kexybiscuit@aosc.io>
Acked-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>