stm32mp1: correct some static analysis tools issues

These issues wer found by sparse:

drivers/st/clk/stm32mp1_clk.c:1524:19:
 warning: incorrect type in assignment (different base types)
    expected restricted fdt32_t const [usertype] *pkcs_cell
    got unsigned int const [usertype] *

plat/st/stm32mp1/plat_image_load.c:13:6:
 warning: symbol 'plat_flush_next_bl_params' was not declared.
 Should it be static?
plat/st/stm32mp1/plat_image_load.c:21:16:
 warning: symbol 'plat_get_bl_image_load_info' was not declared.
 Should it be static?
plat/st/stm32mp1/plat_image_load.c:29:13:
 warning: symbol 'plat_get_next_bl_params' was not declared.
 Should it be static?

plat/st/stm32mp1/bl2_io_storage.c:40:10:
 warning: symbol 'block_buffer' was not declared. Should it be static?

Signed-off-by: Yann Gautier <yann.gautier@st.com>
diff --git a/drivers/st/clk/stm32mp1_clkfunc.c b/drivers/st/clk/stm32mp1_clkfunc.c
index d4c69cb..078d803 100644
--- a/drivers/st/clk/stm32mp1_clkfunc.c
+++ b/drivers/st/clk/stm32mp1_clkfunc.c
@@ -265,11 +265,11 @@
  * This function gets the pointer to a rcc-clk property from its name.
  * It reads the values indicated inside the device tree.
  * Length of the property is stored in the second parameter.
- * Returns pointer if success, and NULL value else.
+ * Returns pointer on success, and NULL value on failure.
  ******************************************************************************/
-const uint32_t *fdt_rcc_read_prop(const char *prop_name, int *lenp)
+const fdt32_t *fdt_rcc_read_prop(const char *prop_name, int *lenp)
 {
-	const uint32_t *cuint;
+	const fdt32_t *cuint;
 	int node, len;
 	void *fdt;