mxs: Rename 'mx28_dram_init' to 'mxs_dram_init'

The DRAM initialization, after SPL has complete, is exactly the same
for all mxs SoCs so we should name it accordinly.

The following boards has been changed:

 * apx4devkit
 * m28evk
 * mx28evk
 * sc_sps_1

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Veli-Pekka Peltola <veli-pekka.peltola@bluegiga.com>
diff --git a/arch/arm/cpu/arm926ejs/mxs/mxs.c b/arch/arm/cpu/arm926ejs/mxs/mxs.c
index a1769fd..c8cda6a 100644
--- a/arch/arm/cpu/arm926ejs/mxs/mxs.c
+++ b/arch/arm/cpu/arm926ejs/mxs/mxs.c
@@ -320,13 +320,13 @@
 }
 #endif
 
-int mx28_dram_init(void)
+int mxs_dram_init(void)
 {
 	struct mxs_spl_data *data = (struct mxs_spl_data *)
 		((CONFIG_SYS_TEXT_BASE - sizeof(struct mxs_spl_data)) & ~0xf);
 
 	if (data->mem_dram_size == 0) {
-		printf("MX28:\n"
+		printf("MXS:\n"
 			"Error, the RAM size passed up from SPL is 0!\n");
 		hang();
 	}