Platform: Update Musca-A with new file structure

This patch updates the Musca-A platform support files with a new file
structure and various other improvements.

Change-Id: Iac0c3aad97f89baf5db32ed331e54b8ed7fced63
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/platform/ext/musca_a.cmake b/platform/ext/musca_a.cmake
index b82ab81..ac9d081 100644
--- a/platform/ext/musca_a.cmake
+++ b/platform/ext/musca_a.cmake
@@ -53,13 +53,13 @@
 if (NOT DEFINED BUILD_CMSIS_CORE)
   message(FATAL_ERROR "Configuration variable BUILD_CMSIS_CORE (true|false) is undefined!")
 elseif(BUILD_CMSIS_CORE)
-  list(APPEND ALL_SRC_C "${PLATFORM_DIR}/target/musca_a/Device/Source/system_cmsdk_musca.c")
+  list(APPEND ALL_SRC_C "${PLATFORM_DIR}/target/musca_a/Device/Source/system_core_init.c")
 endif()
 
 if (NOT DEFINED BUILD_RETARGET)
   message(FATAL_ERROR "Configuration variable BUILD_RETARGET (true|false) is undefined!")
 elseif(BUILD_RETARGET)
-  list(APPEND ALL_SRC_C "${PLATFORM_DIR}/target/musca_a/Device/Source/platform_retarget_dev.c")
+  list(APPEND ALL_SRC_C "${PLATFORM_DIR}/target/musca_a/Device/Source/device_definition.c")
 endif()
 
 if (NOT DEFINED BUILD_UART_STDOUT)
@@ -158,7 +158,7 @@
 if (NOT DEFINED BUILD_FLASH)
   message(FATAL_ERROR "Configuration variable BUILD_FLASH (true|false) is undefined!")
 elseif(BUILD_FLASH)
-  list(APPEND ALL_SRC_C "${PLATFORM_DIR}/target/musca_a/CMSIS_Driver/Driver_Flash.c")
+  list(APPEND ALL_SRC_C "${PLATFORM_DIR}/target/musca_a/CMSIS_Driver/Driver_QSPI_Flash.c")
   # As the SST area is going to be in RAM, it is required to set SST_CREATE_FLASH_LAYOUT
   # to be sure the SST service knows that when it starts the SST area does not contain any
   # valid SST flash layout and it needs to create one.