platform/x86: thinkpad_acpi: consistently check fan_get_status return.

Clang static analysis returns this false positive
thinkpad_acpi.c:8926:19: warning: The left operand
  of '!=' is a garbage value
  (status != 0) ? "enabled" : "disabled", status);
   ~~~~~~ ^

The return of fan_get_status* is checked inconsistenly.
Sometime ret < 0 is an error, sometimes !ret.
Both fan_get_status() and fan_get_status_safe() return
0 on success and return negative otherwise.  Change
the checks for error, ret < 0, into checks for
not success, !ret.

Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20220312145327.1398510-1-trix@redhat.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Author: Tom Rix

drivers/platform/x86/thinkpad_acpi.c

@@ -8285,7 +8285,7 @@ static int fan_set_enable(void)
 	case TPACPI_FAN_WR_ACPI_FANS:
 	case TPACPI_FAN_WR_TPEC:
 		rc = fan_get_status(&s);
-		if (rc < 0)
+		if (rc)
 			break;
 
 		/* Don't go out of emergency fan mode */
@@ -8304,7 +8304,7 @@ static int fan_set_enable(void)
 
 	case TPACPI_FAN_WR_ACPI_SFAN:
 		rc = fan_get_status(&s);
-		if (rc < 0)
+		if (rc)
 			break;
 
 		s &= 0x07;
@@ -8843,7 +8843,7 @@ static void fan_suspend(void)
 	/* Store fan status in cache */
 	fan_control_resume_level = 0;
 	rc = fan_get_status_safe(&fan_control_resume_level);
-	if (rc < 0)
+	if (rc)
 		pr_notice("failed to read fan level for later restore during resume: %d\n",
 			  rc);
 
@@ -8864,7 +8864,7 @@ static void fan_resume(void)
 
 	if (!fan_control_allowed ||
 	    !fan_control_resume_level ||
-	    (fan_get_status_safe(&current_level) < 0))
+	    fan_get_status_safe(&current_level))
 		return;
 
 	switch (fan_control_access_mode) {
@@ -8918,7 +8918,7 @@ static int fan_read(struct seq_file *m)
 	case TPACPI_FAN_RD_ACPI_GFAN:
 		/* 570, 600e/x, 770e, 770x */
 		rc = fan_get_status_safe(&status);
-		if (rc < 0)
+		if (rc)
 			return rc;
 
 		seq_printf(m, "status:\t\t%s\n"
@@ -8929,7 +8929,7 @@ static int fan_read(struct seq_file *m)
 	case TPACPI_FAN_RD_TPEC:
 		/* all except 570, 600e/x, 770e, 770x */
 		rc = fan_get_status_safe(&status);
-		if (rc < 0)
+		if (rc)
 			return rc;
 
 		seq_printf(m, "status:\t\t%s\n",