staging: csr: replace calls to kmalloc and memset with kzalloc

the kzalloc does allocates memory and sets the data at the memory
which is allocated to 0,

The driver does uses the kmalloc and memset at some points in the code
replace them with a single call to kzalloc

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Acked-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>