Fix incorrect memory validation for g_malloc*()

Fix incorrect memory validation for g_malloc*()

g_malloc*() will always return a valid memory address. If the
device is in out of memory case, g_malloc*() will assert.
Hence no need to validate the return value against NULL.

g_malloc*() will always return a memory address which is of type void *.
It doesn't make any sense to typecast this return address to another
pointer address. Ex: char *p = (char *)g_malloc0(..);

Change-Id: I84e772ea2879f2e00a9232922638e19075fd1c7f
Signed-off-by: Injun Yang <injun.yang@samsung.com>