stm32mp1: add 800 MHz profile support

The STM32MP1 series is available in 3 different lines which are pin-to-pin
compatible:
- STM32MP157: Dual Cortex-A7 cores, Cortex-M4 core @ 209 MHz,
              3D GPU, DSI display interface and CAN FD
- STM32MP153: Dual Cortex-A7 cores, Cortex-M4 core @ 209 MHz
              and CAN FD
- STM32MP151: Single Cortex-A7 core, Cortex-M4 core @ 209 MHz

Each line comes with a security option (cryptography & secure boot)
& a Cortex-A frequency option :

- A : Cortex-A7 @ 650 MHz
- C : Secure Boot + HW Crypto + Cortex-A7 @ 650 MHz
- D : Cortex-A7 @ 800 MHz
- F : Secure Boot + HW Crypto + Cortex-A7 @ 800 MHz

This patch adds the support of STM32MP15xD and STM32MP15xF in U-Boot.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/doc/board/st/stm32mp1.rst b/doc/board/st/stm32mp1.rst
index ee42af6..b7a0fbf 100644
--- a/doc/board/st/stm32mp1.rst
+++ b/doc/board/st/stm32mp1.rst
@@ -25,6 +25,14 @@
  - Standard connectivity, widely inherited from the STM32 MCU family
  - Comprehensive security support
 
+Each line comes with a security option (cryptography & secure boot) and
+a Cortex-A frequency option:
+
+ - A : Cortex-A7 @ 650 MHz
+ - C : Secure Boot + HW Crypto + Cortex-A7 @ 650 MHz
+ - D : Cortex-A7 @ 800 MHz
+ - F : Secure Boot + HW Crypto + Cortex-A7 @ 800 MHz
+
 Everything is supported in Linux but U-Boot is limited to:
 
  1. UART