dmaengine/amba-pl08x: pass (*ptr) to sizeof() instead of (struct xyz)

As mentioned in Documentation/CodingStyle,

The preferred form for passing a size of a struct is the following:
   p = kmalloc(sizeof(*p), ...);

The alternative form where struct name is spelled out hurts readability and
introduces an opportunity for a bug when the pointer variable type is changed
but the corresponding sizeof that is passed to a memory allocator is not.

This patch replaces (struct xyz) with *ptr at several occurrences in driver.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>