Add a new frequency entry to the QSPI core clock configuration table
to support 75MHz (75 * 4 = 300MHz).
This is achieved by using the GPLL0 600MHz source with a divisor of 2.
Providing a 300MHz core clock allows for more granular control over
the physical bus speed (SCK). Specifically, it enables a stable 75MHz
SPI bus frequency via a clean 1/4 divider, which is an optimization
target for improving boot times on Bluey/Quenbi platforms.
BUG=b:478226455
TEST=Verified that 'clock_configure_qspi' can correctly look up and
set the 300MHz frequency in romstage.
Change-Id: I5320a68ff50a0d79daa2fc855b18b0f3ae819bbe
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/90886
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Derek Huang <derekhuang@google.com>
54e7b5734f