vboot: remove leftover TPM_PCR_GBB constants

These constants were left behind after the code using them
was relocated in CB:34510.

BUG=b:124141368, chromium:972956
TEST=make clean && make test-abuild
BRANCH=none

Change-Id: I6ce7c969a9e9bdf6cdce3343ba666a08b3521f27
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40358
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/security/vboot/secdata_tpm.c

@@ -56,9 +56,6 @@
 		}							\
 	} while (0)
 
-#define TPM_PCR_GBB_FLAGS_NAME "GBB flags"
-#define TPM_PCR_GBB_HWID_NAME "GBB HWID"
-
 static uint32_t safe_write(uint32_t index, const void *data, uint32_t length);
 
 static uint32_t read_space_firmware(struct vb2_context *ctx)