efi/libstub/tpm: Make function efi_retrieve_tpm2_eventlog_1_2() static

Fixes the following sparse warning:

drivers/firmware/efi/libstub/tpm.c:62:6: warning:
 symbol 'efi_retrieve_tpm2_eventlog_1_2' was not declared. Should it be static?
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180504060003.19618-12-ard.biesheuvel@linaro.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

drivers/firmware/efi/libstub/tpm.c

@@ -59,7 +59,7 @@ void efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg)
 
 #endif
 
-void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
+static void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
 {
 	efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
 	efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;