[PATCH v3] common/efi: fix Rule 2.1 violation in read_file()

[Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>]

MISRA C Rule 2.1 states: "A project shall not contain unreachable code."

The return statements in the 'read_file()' function is unreachable due
to function 'PrintErrMesg()' which has 'noreturn' attribute:
        PrintErrMesg(name, ret);
        /* not reached */
        return false;
    }

No explicit return statement is needed here. Remove the statement and
write a justification comment instead. No functional changes.

Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
---
Link to v2:
https://patchew.org/Xen/c20a58f24875806adfaf491f9c6eef2ca8682d18.1755711594.git.dmytro._5Fprokopchuk1@xxxxxxxx/

Changes in v3:
- removed unreachable code instead of deviation
- updated commit subject and message

Test CI pipeline:
https://gitlab.com/xen-project/people/dimaprkp4k/xen/-/pipelines/1996439444
---
 xen/common/efi/boot.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 50ff1d1bd2..325de05b18 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -851,9 +851,13 @@ static bool __init read_file(EFI_FILE_HANDLE dir_handle, 
CHAR16 *name,
     PrintErr(what);
     PrintErr(L" failed for ");
     PrintErrMesg(name, ret);
-
-    /* not reached */
-    return false;
+    /*
+     * No explicit return statement is needed here because 'PrintErrMesg()' is
+     * marked as 'noreturn', which guarantees that it never returns control to
+     * the caller. If the 'noreturn' attribute of 'PrintErrMesg()' is removed
+     * in the future, compiler will emit an error about the missing return
+     * statement (build-time safeguard).
+     */
 }
 
 static bool __init read_section(const EFI_LOADED_IMAGE *image,
-- 
2.43.0