Remove an extra function call in primask::read

[yvt]

There doesn't seem to be any reason why the call to __primask_r should be wrapped by another function call. read_raw (the function being removed by this PR) is not #[inline], so it did hurt performance when compiled without LTO.

Compare with faultmask::read:

cortex-m/src/register/faultmask.rs

Lines 26 to 35 in 7481f09

	/// Reads the CPU register
	#[inline]
	pub fn read() -> Faultmask {
	let r: u32 = call_asm!(__faultmask_r() -> u32);
	if r & (1 << 0) == (1 << 0) {
	Faultmask::Inactive
	} else {
	Faultmask::Active
	}
	}

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @thalesfragoso (or someone else) soon.

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[jonas-schievink]

bors r+

[bors]

Build succeeded:

• ci-linux (1.38.0)
• ci-linux (stable)
• clippy
• rustfmt