efi/cper: Add a new helper function to print bitmasks

efi/cper: Add a new helper function to print bitmasks

Add a helper function to print a string with names associated
to each bit field.

A typical example is:

	const char * const bits[] = {
		"bit 3 name",
		"bit 4 name",
		"bit 5 name",
	};
	char str[120];
        unsigned int bitmask = BIT(3) | BIT(5);

	#define MASK  GENMASK(5,3)

	cper_bits_to_str(str, sizeof(str), FIELD_GET(MASK, bitmask),
			 bits, ARRAY_SIZE(bits));

The above code fills string "str" with "bit 3 name|bit 5 name".

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>