Remove MAYBE_STATIC_BSS and ENV_STAGE_HAS_BSS_SECTION

After removal of CAR_MIGRATION there are no more reasons
to carry around ENV_STAGE_HAS_BSS_SECTION=n case.

Replace 'MAYBE_STATIC_BSS' with 'static' and remove explicit
zero-initializers.

Change-Id: I14dd9f52da5b06f0116bd97496cf794e5e71bc37
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40535
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/ec/google/chromeec/ec.c

@@ -1343,7 +1343,7 @@ static void google_chromeec_log_uptimeinfo(void)
 /* Cache and retrieve the EC image type (ro or rw) */
 enum ec_image google_chromeec_get_current_image(void)
 {
-	MAYBE_STATIC_BSS enum ec_image ec_image_type = EC_IMAGE_UNKNOWN;
+	static enum ec_image ec_image_type = EC_IMAGE_UNKNOWN;
 
 	if (ec_image_type != EC_IMAGE_UNKNOWN)
 		return ec_image_type;

src/ec/google/chromeec/ec_lpc.c

@@ -387,7 +387,7 @@ void google_chromeec_ioport_range(uint16_t *out_base, size_t *out_size)
 
 int google_chromeec_command(struct chromeec_command *cec_command)
 {
-	MAYBE_STATIC_BSS int command_version = 0;
+	static int command_version;
 
 	if (command_version <= 0)
 		command_version = google_chromeec_command_version();