community/soc-qcom-msm8953: fix modem script

1. /dev/disk/by-partlabel/persist is mounted twice with diffrent dirs.
umount $PERSIST_DEV unmout the other one
2. /lib/firmware/postmarketos does not exist on xiaomi-daisy, use mkdir -p

Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/6967>

device/community/soc-qcom-msm8953/APKBUILD

@@ -4,7 +4,7 @@
 # Co-Maintainer: Danila Tikhonov (JIaxyga) <danila@mainlining.org>
 pkgname=soc-qcom-msm8953
 pkgdesc="Common package for Qualcomm MSM8953 devices"
-pkgver=14
+pkgver=15
 pkgrel=0
 url="https://postmarketos.org"
 license="BSD-3-Clause"
@@ -75,5 +75,5 @@ sha512sums="
 8aadc874c8a334e46c7bf630874c3035070aa7b9052deba1a28ae059ab9d63dd99dfb82c1a58d09da5063ad250de813e3974e040ce938a53347e390ce2e450eb  soc-qcom-msm8953-f6dfc9b072e74b0ab2afcf452bc106242049ef28.tar.gz
 3a4a9322839d4b3ef9d79668a37840a9f444954759ae3c512e694051d2f9a2573db42ad6c4c1a5c75eeb861232a27ba1a8cef9b503decd54ead25a96e3dd6f98  q6voiced.conf
 4f9af3c582ae611d42fc058f949f60a96fc7cc884052e4c9f82e0292d57bba3b3cb8ace1d512b5a59535caa633be8558246a7519c2d067b7980f4088f452df6d  adreno-a506-quirks.sh
-d4fd0f3406c9f004e9cae7bc500c5713aab75f102f8e3ea1af820865f01eb03def01cd9ed3e8a184c7dfc22ab419628fad17957a3782885d96eb36e94461e842  moto-modem-rfs-setup.openrc
+0d2539681c6a8e6f222ab378dc688a2b4a21dc61e393b4fe42420abb7ffd9ad1b8f69b10fbe18995f10b13cb870130f616b0b37a38f253e12041dd36391c613f  moto-modem-rfs-setup.openrc
 "

device/community/soc-qcom-msm8953/moto-modem-rfs-setup.openrc

@@ -28,11 +28,11 @@ start()
 		mkdir -p $PERSIST_PATH
 		mount $PERSIST_DEV -o ro,noatime $PERSIST_PATH
 
-		mkdir $MODEM_FIRMWARE_DIR
+		mkdir -p $MODEM_FIRMWARE_DIR
 
 		cp -R "$PERSIST_PATH"/rfs/msm/mpss/ "$MODEM_FIRMWARE_DIR"/readwrite
 
-		umount $PERSIST_DEV
+		umount $PERSIST_PATH
 		rmdir $PERSIST_PATH
 	fi