docs(build): update GCC to 12.2.Rel1 version

Updating toolchain to the latest production release version
12.2.Rel1 publicly available on https://developer.arm.com/

We build TF-A in CI using:
AArch32 bare-metal target (arm-none-eabi)
AArch64 ELF bare-metal target (aarch64-none-elf)

Change-Id: Ib603cf7417e6878683a1100d5f55311188e36e8e
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
diff --git a/docs/getting_started/prerequisites.rst b/docs/getting_started/prerequisites.rst
index bf10ecf..a3f8cc8 100644
--- a/docs/getting_started/prerequisites.rst
+++ b/docs/getting_started/prerequisites.rst
@@ -26,7 +26,7 @@
 |TF-A| can be built with any of the following *cross-compiler* toolchains that
 target the Armv7-A or Armv8-A architectures:
 
-- GCC >= 11.3.Rel1 (from the `Arm Developer website`_)
+- GCC >= 12.2.Rel1 (from the `Arm Developer website`_)
 
    You will need the targets ``arm-none-eabi`` and ``aarch64-none-elf`` for
    AArch32 and AArch64 builds respectively.