Adding the grub rebuild command after Gcov kernel Install

Few times grub-rebuild is not properly happening or
not taking care after Gcov kernel installed. Hence The Gcov
kernel doesnot listing in the grub entry during boot.
So added the grub rebuild command, with which it builds the
Gcov kernel properly.

Signed-off-by: Naresh Bannoth <nbannoth@in.ibm.com>

Author: Naresh-ibm

testcases/GcovSetup.py

@@ -199,6 +199,7 @@ def build_and_boot(self, config_path):
             cmd = f"make -j modules_install && make install"
             if not self.cv_HOST.host_run_command(cmd):
                 self.fail("module installation failed")
+            self.cv_HOST.host_run_command("grub2-mkconfig -o /boot/grub2/grub.cfg")
         except Exception:
             self.fail("compile and build of gcov kernel failed")