usb: dwc2: set ahbcfg parameter for STM32MP15 OTG HS and FS

STM32MP15 ahbcfg register default value sets Burst length/type (HBSTLEN)
to Single (32-bit accesses on AHB), which is not recommended, according
to STM32MP157 Reference manual [1].
This patch sets Burst length/type (HBSTLEN) so that bus transactions
target 16x32 bit accesses. This improves OTG controller performance.

[1] https://www.st.com/resource/en/reference_manual/dm00327659.pdf, p.3149

Acked-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20210105094855.30763-2-amelie.delaunay@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>