infra/common: remove manual reboot step from secure boot doc

Neoverse Reference Design FVPs version 11.15.26 or higher support reboot
feature. It is not required to manually close and relaunch the FVP to
simulate a reboot behaviour. Hence remove the step from secure boot
documentation which describes to manually close and relaunch the model.
Suggested-by: Rohit Mathew <rohit.mathew@arm.com>
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>
Change-Id: I2a9a5e890160ef211a0a2af9b50933549de84513

docs/infra/common/secure-boot.rst

@@ -243,18 +243,12 @@ on the very first boot for validating the secure boot.
 9. Press Escape and press F10 to save. Ensure that the “Current Secure Boot
    State” is set as “Enabled”.
 10. Press Escape and select the “continue” option.
-11. Prompts the user to press the “Enter”. Press Enter key which then reboots the
-    system.
-12. Make sure to close the model using “Cross Mark” on the FVP UI window titled
-    'Fast Models - <platform_name>' after this. If model does not close then
-    press “ctrl-c” to close it. Here, <platform_name> is one of those listed in
-    `Platform Names`_.
-
-Relaunch the model again with repeat the steps listed above to perform a secure
-boot (but skip the steps to enroll the signatures). The platform boots up to
-busybox login prompt with secure boot enabled. If the authentication of the grub
-or the linux kernel fails, the boot fails and the user is notified about the
-authentication failure.
+11. Prompts the user to press the “Enter”. Press Enter key which then reboots
+    the system.
+
+The platform boots up to busybox login prompt with secure boot enabled. If the
+authentication of the grub or the linux kernel fails, the boot fails and the
+user is notified about the authentication failure.
 
 To confirm that the boot is indeed a secure boot, the linux kernel messages
 can be looked up. The following messages would appear in the linux boot log in