Fix spelling of 'platform' in comments and doc

Replace platfrom -> platform.

This is a frequent spelling bug.

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/video/mbx/mbxfb.c b/drivers/video/mbx/mbxfb.c
index 01f77bc..afea9ab 100644
--- a/drivers/video/mbx/mbxfb.c
+++ b/drivers/video/mbx/mbxfb.c
@@ -693,7 +693,7 @@
 	unsigned long tmp;
 	int i;
 
-	/* FIXME: use platfrom specific parameters */
+	/* FIXME: use platform specific parameters */
 	/* setup SDRAM controller */
 	write_reg_dly((LMCFG_LMC_DS | LMCFG_LMC_TS | LMCFG_LMD_TS |
 		LMCFG_LMA_TS),