disk: part: rename parameter of lba512_muldiv()

div_by is a misleading parameter name, when we are doing >> div_by.
Rename it to right_shift.
Reported-by: NSimon Glass <sjg@chromium.org>
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>

disk/part.c

@@ -104,17 +104,18 @@ typedef lbaint_t lba512_t;
 #endif
 
 /*
- * Overflowless variant of (block_count * mul_by / 2**div_by)
- * when div_by > mul_by
+ * Overflowless variant of (block_count * mul_by / 2**right_shift)
+ * when 2**right_shift > mul_by
  */
-static lba512_t lba512_muldiv(lba512_t block_count, lba512_t mul_by, int div_by)
+static lba512_t lba512_muldiv(lba512_t block_count, lba512_t mul_by,
+			      int right_shift)
 {
 	lba512_t bc_quot, bc_rem;
 
 	/* x * m / d == x / d * m + (x % d) * m / d */
-	bc_quot = block_count >> div_by;
-	bc_rem  = block_count - (bc_quot << div_by);
-	return bc_quot * mul_by + ((bc_rem * mul_by) >> div_by);
+	bc_quot = block_count >> right_shift;
+	bc_rem  = block_count - (bc_quot << right_shift);
+	return bc_quot * mul_by + ((bc_rem * mul_by) >> right_shift);
 }
 
 void dev_print (struct blk_desc *dev_desc)