acpigen: export acpigen_write_field_name

It will be used in a follow-up change.

Change-Id: If89f9569c33949995d3b45a5f871ff2cb84a6610
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68787
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/acpi/acpigen.c

@@ -532,7 +532,7 @@ static void acpigen_write_field_offset(uint32_t offset, uint32_t current_bit_pos
 	acpigen_write_field_length(diff_bits);
 }
 
-static void acpigen_write_field_name(const char *name, uint32_t size)
+void acpigen_write_field_name(const char *name, uint32_t size)
 {
 	acpigen_emit_simple_namestring(name);
 	acpigen_write_field_length(size);