ram: stm32mp1: add size and addr parameter to test all

Add size and addr parameter to test "All" to override the default
value (4kB and STM32_DDR_BASE) used in tests with these optional
parameters: [size] or [addr].

When other optional parameters are present before [addr],
they are replaced by default value:
- [loop] = "1"
- [pattern] = "-" (new: force default pattern)

Example to use:

DDR>test 0 1 0x20000

DDR>test 0 1 0x1000000 0xD0000000

Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>