fix(semihosting): fix seek call failure check

The code checks that the semihosting seek call return value is not
zero instead of a negative value when there is an error condition.
This defect has been fixed.

In [1], possible return values for semihosting seek calls are
mentioned.

[1]: https://github.com/ARM-software/abi-aa/blob/main/semihosting/
semihosting.rst#sys-seek-0x0a

Change-Id: I70f09e98323e9c5bf4eeda322ac065e855e256fc
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/changelog.yaml b/changelog.yaml
index d3e235d..dd1f804 100644
--- a/changelog.yaml
+++ b/changelog.yaml
@@ -649,6 +649,9 @@
       - title: Context Management
         scope: context mgmt
 
+      - title: Semihosting
+        scope: semihosting
+
   - title: Drivers
 
     subsections:
diff --git a/lib/semihosting/semihosting.c b/lib/semihosting/semihosting.c
index e0845c1..163a82d 100644
--- a/lib/semihosting/semihosting.c
+++ b/lib/semihosting/semihosting.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2022, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -64,8 +64,10 @@
 
 	result = semihosting_call(SEMIHOSTING_SYS_SEEK, (uintptr_t)&seek_block);
 
-	if (result != 0) {
+	if (result < 0) {
 		result = semihosting_call(SEMIHOSTING_SYS_ERRNO, 0);
+	} else  {
+		result = 0;
 	}
 
 	return result;