std_detect: Fix link in mips.rs

[taiki-e]

stdarch/crates/std_detect/src/detect/os/linux/mips.rs

Line 18 in b1edbf9

// [hwcap]: https://github.com/torvalds/linux/blob/master/arch/arm64/include/uapi/asm/hwcap.h

This currently refers arm64 hwcap.h, but this file is for mips. (The values that used in this file is correct and just a link is wrong.)

[rustbot]

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