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: If61ac9d2628ce9432b767d588f991ca4c625fcf6
Signed-off-by: Injun Yang <injun.yang@samsung.com>