platform: msm_shared: Implement mmc_page_size function

Implement mmc_page_size function to fix compilation targets
that dont support SDHCI.

Change-Id: Ie692af01c7694440ab692517cd41d52193b5191c
diff --git a/platform/msm_shared/mmc.c b/platform/msm_shared/mmc.c
index 25d619c..75f937f 100644
--- a/platform/msm_shared/mmc.c
+++ b/platform/msm_shared/mmc.c
@@ -85,7 +85,7 @@
 static unsigned int
 mmc_boot_bam_setup_desc(unsigned int *data_ptr,
 			    unsigned int data_len, unsigned char direction);
-
+uint32_t mmc_page_size();
 
 #endif
 
@@ -159,6 +159,11 @@
 									 24);
 }
 
+uint32_t mmc_page_size()
+{
+	return BOARD_KERNEL_PAGESIZE;
+}
+
 void mmc_mclk_reg_wr_delay()
 {
 	if (mmc_host.mmc_cont_version)