configs: stm32mp: cleanup the stm32mp15 file

Remove STM32_SYSRAM_END and clean the comments in stm32mp15_common.h file
after moving some CONFIG to Kconfig: CONFIG_SYS_CBSIZE,
CONFIG_SPL_MAX_FOOTPRINT, CONFIG_SYS_SPL_MALLOC_START and
CONFIG_SYS_SPL_MALLOC_SIZE.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/include/configs/stm32mp15_common.h b/include/configs/stm32mp15_common.h
index 08a7248..fc636be 100644
--- a/include/configs/stm32mp15_common.h
+++ b/include/configs/stm32mp15_common.h
@@ -16,10 +16,6 @@
 #define CONFIG_SYS_SDRAM_BASE			STM32_DDR_BASE
 
 /*
- * Console I/O buffer size
- */
-
-/*
  * For booting Linux, use the first 256 MB of memory, since this is
  * the maximum mapped by the Linux kernel during initialization.
  */
@@ -28,13 +24,6 @@
 /* Extend size of kernel image for uncompression */
 #define CONFIG_SYS_BOOTM_LEN		SZ_32M
 
-/* SPL support */
-#ifdef CONFIG_SPL
-/* SPL use DDR */
-
-/* Restrict SPL to fit within SYSRAM */
-#define STM32_SYSRAM_END		(STM32_SYSRAM_BASE + STM32_SYSRAM_SIZE)
-#endif /* #ifdef CONFIG_SPL */
 /*MMC SD*/
 #define CONFIG_SYS_MMC_MAX_DEVICE	3