lib: newlib: Remove internal _sbrk lock

This commit removes the lock inside the newlib internal `_sbrk`
function, which is called by `malloc` when additional heap memory is
needed.

This lock is no longer required because any calls to the `malloc`
function are synchronised by the `__malloc_lock` and `__malloc_unlock`
functions.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

lib/libc/newlib/libc-hooks.c

@@ -268,14 +268,10 @@ __weak void _exit(int status)
 	}
 }
 
-static LIBC_DATA SYS_SEM_DEFINE(heap_sem, 1, 1);
-
 void *_sbrk(intptr_t count)
 {
 	void *ret, *ptr;
 
-	/* coverity[CHECKED_RETURN] */
-	sys_sem_take(&heap_sem, K_FOREVER);
 	ptr = ((char *)HEAP_BASE) + heap_sz;
 
 	if ((heap_sz + count) < MAX_HEAP_SIZE) {
@@ -285,9 +281,6 @@ void *_sbrk(intptr_t count)
 		ret = (void *)-1;
 	}
 
-	/* coverity[CHECKED_RETURN] */
-	sys_sem_give(&heap_sem);
-
 	return ret;
 }
 __weak FUNC_ALIAS(_sbrk, sbrk, void *);